Brand New VPI Prime 21 Turntable with Gimbal Arm has loose counterweight adjustment thumbscrew, causes tracking force to continually drift.

Glad to hear that you continue to enjoy the new table. Nice measurement

Sorry to hear about your issues, perhaps I can offer some assistance.

1.     VTF rear adjustment knob - Have you tried swapping out the counterweight from the replacement arm with the original arm? This might correct your issue.

2.     Bearing slop - there should be no vertical or horizontal play with a captive (gimbal) bearing arm. Unless you have a micro torque wrench, the appropriate torque setting and some Loctite, I would not attempt to perform any bearing adjustments. Send it back to VPI - they will make it right.

3.     Speed, Wow and flutter issues - there will be some very slight speed issues at start up until the bearing warms up. This is normal with any table without a feedback loop motor controller. Fortunately (IME) the speed variance in not audible. Steady state speed (33.33rpm) should be set after the table has warmed up. Do not use too much lithium grease when lubricating the platter spindle as it may cause a temporary vapour lock which will cause additional drag on the motor and may cause inconsistent micro speed variations.

4.     Lemo wire causing horizontal bias force - this is bi-product of any tonearm that has tonearm wires exiting either from the top or bottom. The wires are twisted for EMI/RFI rejection but will have an inherent rotation torque. This rotational torque can be mitigated by reducing the wire's dielectric memory with a gentle application of heat. In summary, the lemo wire can be tuned through heat, manipulation, and proper dressing.

Thank you very much for your suggestions. I sincerely appreciate the time it took you to post this!

I have not tried a countereeight from one of the two replacement arms on my original arm.

I did however, think that possibly the inner circumference of my original counterweight may have been out of tolerance. When. I have the countereeight off, just by squeezing the plastic sled that the countereeight slides onto, causes the countereeight adjustment thumbscrew to have some resistance.

I would imagine that the small hex head set screw on the countereeight does not, by itself, have enough surface area to add the resistance that I can with my fingers by squeezing the plastic sled. I sent both slop gimbal bearing arms back to VPI as I received them one at a time. I wish I would have tried the countereeight swap as you suggested! The thing that bothers me, is that I asked Jim to please have the second replacement arm tested before shipping to me. Obviously that did not happen. The rattling loose bearings really become obvious after the arm is mounted on the VTA platform. I noticed both arms gimbal bearings rattled when lifting the arm off of the rest post with the fingerlift. I have videos on YouTube that I sent links to Jim as the file sizes was way too large to email and I don't have a file sharing platform.

As far as the rattling or jingling gimbal bearings, I would in no way attempt to tighten them myself. I would fear the ruination by improper excessive torque. Whatever vendor VPI is using is slipping on the QC! I sent two arms back. Jim in customer service told me there was nothing else they could do. Just keep the original arm with good bearings. I literally just gave up! It was costing me a small fortune just to FedEx a tonearm. I tightened the living heck out of the countereeight hex head set screw on my original arm, so at least VTF is stable with the original arm now.

Speed: my table runs fast. I use the upper-most motor pulley. I checked the line frequency from Pennsylvania Power and Light which drifts between 59.99 Hz to 60.02 Hz. Not bad at all. At most with those readings, I should only be off on RPM by 0.01 or 0.02 at the most. The speed increases thermally. The only way to slow it down would be to buy a line frequency controller. But, I wouldn't want one without a feedback loop to control line frequency as speed varies at the platter.

Lubrication: I can get as much as 0.25% wow after the lubrication stops working. At that point, I remove the platter, clean all mating surfaces with a microfiber cloth and then reapply the "Super Lube" grease with PTFE. I place a thin coating on the bearing shaft and a small dollop on the ball bearing. I don't think, or at least I hope that's not too much. I watched Mat's video... I then wash the belt and the platter rim with a tiny bit of "Dawn" dishwashing liquid in distilled water. You have to be very careful of pH with aluminum. Anything caustic or alkaline will etch aluminum. Anyway, when all is back together and I allow the turntable to run for an hour or so, the wow is back to normal at 0.02% RMS. Im at a loss as to what happens in about 4 weeks when I need to clean and relubricate.

Lemo Wire: my original arm with good bearings can achieve zero bias when the red dot on the Lemo connector is where it is supposed to be (no twist clockwise or counterclockwise). I would not try heat myself. This should have been set correctly at the arm vendor factory. Once again, was quality control carried out?

Lastly my walnut laminate is peeling off of the plinth on the bottom front. It may have been that way when I received the unit. It's barely noticeable now, but I fear as time progresses, the loss of adhesion may open up a much larger area. At first I thought it was just a flat spot on the MDF underneath the laminate, but placing a mirror under the front edge of the plinth, I could see the plastic walnut laminate was not attached to the MDF. I'll have to get a picture.

Again my appreciation for your help. Forums are great ways to share ideas and help others.

I took some pictures last evening of the plastic walnut laminate veneer peeling off of the front of the Prime 21. I'll post below. One is the front where you can see the laminate lifting and the other is using a selfie camera on my phone from underneath the plinth, (quite out of focus), but it illustrates the issue of the adhesive failing. I do believe it will get worse over time.

@Brf Check this out. This is a cheap replacement belt that I bought on eBay. 2 for $27. The belt performs amazingly well.

% Wow RMS dropped down to 0.02% and speed is almost dead nuts on at 33.34 RPM. This is approaching direct drive specifications! I'm sure by playing with motor to platter distance, I could dial in speed precisely...

I'm not sure I'm going to use the belt long-term though. I think I'm going to put the VPI belt that was supplied with the turntable back on.

Just thought you may find it interesting.

VPI drive belts are simply an o-ring cord (extrusion) with the ends fused together. The smaller belts are a single piece construction utilizing injection, compression, transfer, etc., molding technology.

O-ring cord can be bought in bulk at a very inexpensive price. With the purchase of a slicing kit, some super glue, and a steady hand, you can easily fuse the two ends together with a high degree of accuracy. If you are so inclined, you can change the length, diameter, durometer, and material composition to suit both your curiosity and personal sonic preference. Enjoy the new table.

Thanks @Brf The new table is definitely a winner. And yes, the scientific part of me wants to experiment with belts.

I was amazed at just how good of a bearing system VPI uses on their turntables when I got the wow down to 0.02% RMS by using a different belt. That's way below the wow that the table is even rated.

VPI rated the table very conservatively. It's amazing how much accuracy is built in. My new Prime 21 is a precision instrument! I'm very pleased with it and the way Mat handled the entire situation.