Redpoint went to very thin, silicone rubber pads under their motor controller.FWIW, I once tried adding a thin (<.5mm) layer of a self-adhesive, non-slip material to the bottom of the coupling discs on which my motor spikes sit. I thought this might reduce the occasional (once every month or two) need to check belt tension and/or improve motor stability and thus dynamics.
In fact, I got one of those unintended consequences. The very tiny amount of rocking this "squidgy" layer allowed caused a "THUMP" when the tape splice went 'round the motor capstan. This was transmitted back through the belt to the platter, where the cartridge picked it up and sent it to the speakers.
I peeled it off. No more thumps. Solid coupling works best for me. I'm sure Twl and the folks at Audiopoints would laugh knowingly.