Hi folks

I wonder if anyone can help. I recently bought drives for my EQ3-2 mount.
However, as soon as it is switched on, the RA drive sets up a vibration in
the scope - everything goes blurry. What is going on? I'm a beginner, but
I'm pretty sure everything is set up right. The scope is balanced; there's
no backlash in the worm gears; everything is screwed up nice and tight; the
tripod is on a brick patio. The tripod legs are aluminium and I know this
isn't the best, but surely this shouldn't be happening. Currently the drive
is essentially unusable.

The motor itself beats quite perceptibly to the touch, and indeed the ear.
I don't know if this is normal or not having nothing to compare it to. Has
anyone else experienced this? I am perfectly willing to believe I have done
something daft, but I cannot for the life of me think what.