VPI rimdrive squeaks

Have you examined the o-ring on the rim driver wheel that contacts the platter? If the periodicity of the noise matches the rotation of the driver wheel, there must be some irregularity in the o-ring. If the periodicity matches the platter rotation (i.e., the time it takes for the platter to rotate 360 degrees), then look at the edge of the platter where it contacts the drive wheel. If all looks well, then I suspect you have a defect within your motor, perhaps a bad bushing or something like that. What you describe is unacceptable in such a product, and since your problem is rather unique, I suspect that one of the above is occurring. But you need to do some homework to figure it out.

Hum and squeak are unrelated phenomena, as you seem to know. Hum with phono reproduction is usually a matter of grounding. First try grounding the turntable metal chassis AND the tonearm to the preamp. Make sure this is a firm connection; I like to use bare wire and scrape any paint or other finish off the chassis in the area of the ground connection, so that the wire really is crimped against the bare metal of the chassis. If you have done that and still have hum, then disconnect one or both grounds from the preamp and see what happens. Another more rare possibility is that with your table the motor is close enough to the cartridge so that its EMI radiations are being picked up. Try shielding the motor in that case. This is a totally solvable problem.

As to squeak, since you have now heard it with two different rim drive motors, I am kinda stumped. Like others say, be sure the rim driver wheel is plane parallel to the platter surface and perpendicular to the driven edge of the platter. Since the squeak is in synch with the drive wheel rotation, examination of the o-ring where it contacts the side of the platter is in order, as others have said and as I mentioned before too. Sorry, you are getting the same ideas from everyone over and over again.