[Omaroo (Chris Malikoff)]

Don't forget the clutches Derek.

Periodic Error Correction can't necessarily compensate for wild jumps like you're experiencing. Still sounds mechanical to me, but see what happens. I'm keen to hear the result! Remember that in AltAz mode you're asking the mount to track in two dimensions at the same time. Remember - PEC training is performed separately on both the RA & Dec axes when in AltAz mode. There is also a "DEC PEC" training mode. Errors are going to come in to play. Apart from PEC training there is a "Train Drives" menu item in your Autostar II controller that takes you through basic gear slop and backlash adjustment.

Another thing - how's your balance? Are you using the appropriate SCT counterweights to offset the camera's weight? The DSI doesn't weight much, but balance is still important.