try as i may i cant get the speed stable, its a belt drive with servo feedback control, a little bit better than the usual garrard quality, but not much, anyone come across this model?, the motor could be goosed as a last resort,

Good luck. Back in that era, I had two new Garrards...a zero 100 and a DD 75 that were both crap. Both with bad motors (I guess...speed would be all over the place.)