I'm still looking for a "lift" plate, but obviously not hard enough
If the Achromat is a similar weight and total thickness to the beogram top platter, then you could try replacing one with t'other.
Thinking about my earlier comments, it would be a shame to attempt removal of the studs, but i still think some form of extra record support ought to be tried perhaps.
Regarding noise from the drive, a little "whirring" is normal and the Beocentre 3500's I helped set up and install back in the day always had a "whine" from the motor, which only occurs on my Gram 3000 if sat on a carpet when running. it may be worth *carefully* up-ending the deck and removing the base to chaeck the motor unit is as correctly suspended as possible and the supply wires are as free as possible and not touching any of the surrounding metalwork and "shorting out" the motor suspension, such as it is.
Another question for you all. is it possible to replace the lid fixings, as mine has an aluminium bar screwed on the back edge to hold everything together...