[Shiraz (Ray)]

my guess would be that it's backlash in RA - DEC looks good.

have you tried tightening up the worm clearance as a first step. The transfer gear clearance may need to be tightened up if the worm clearance is OK. easy to check if there is a backlash problem by seeing how much the scope can be rocked in RA by hand - if you can feel it clonking back and forth, then it needs tightening. You could also try deliberately unbalancing the scope in RA so that the worm always sits on one side of the gear, but it is still a good idea to tweak up the backlash.

these mounts make strange noises when starting and stopping a slew. You can make them less noisy with careful adjustment, but it does not seem to make much difference to performance. However, the Dec noise you describe could possibly be due to a slightly over-tightened worm, so it would probably be worth checking that as well.

persevere - these are good mounts, but they require adjustments every few months to keep them in peak condition.