I'll get one simple thing out of the way first - with a digital drive the fastest "slew" is 16x or ~4 degrees per minute, which is still really slow if you are using the word "slew". It's a guiding speed, not a slewing-to-a-new-position speed.?

Are you sure that the worm is not engaging the gear, ie if you move the scope manually in RA or DEC can you see the main gear turning ? Normally the clutches would slip but the main gear would stay fixed.