My 10" f/6.8 jittered the first time I put it all back together after taking it all apart to clean, lube and paint it. I found a loose bolt holding the Dec housing to the polar axis and tightened it and then hit the wrench with a rubber mallet a few times. You may have a loose screw somewhere.
The number of possible failures in Caves mount is limited. My tube is 8" longer than yours and damps out after ringinginging. You have to get all the backlash out and adjust the clutches.
If you swapped out the tube elements (focuser, spider, mirror cell, etc.) then it's a good chance your tube is not correctly balanced by that tube weight.
Someone had changed everything before i bought it as he gave me the old tube and Cave parts. The mirror is Cervit and was refigured by Galaxy in 1988. The scope has a Novak spider and mirror cell , the focuser is the stock unit that Cave used and 2ndary is smaller than the stock version. Tube has great balance as it is. Guess it is really not a Cave anymore other than the focuser, rotating rings and finder. Mirror is insane good and worth having a much better mount and will try to find a used non GO-TO AP 900 or 1200.
Edited by CHASLX200, 15 January 2019 - 07:47 PM.