I think I've pretty well worked through all my startup issues with this mount, except this one.
There is a very significant vibration, lasting for 5 seconds or more, when the tube/mount is touched (e.g., focusing, a bit of a breeze). It's entirely the RA assembly that's vibrating. No adjustment in the locking screw for the clutch can reduce it beyond this (it gets worse as the screw is loosened). No adjustment of the positions of the two counterweights makes any difference.
The vibration is significantly greater (both in amplitude and duration) when the tube is heavy (e.g., a 30 pound SCT OTA) than when the tube is light (e.g., small refractor).
Do others have this issue? I've talked about this with iOptron support, so far with no results.
Any useful suggestions?