Inside the SeaStar helm pump
are a series of cylindrical metal pistons (some of them circled in blue below). Sounds like they could be going clunk for some reason. Ive heard them do this on occasion on SeaStar and Capilano helms with no apparent issue, but it could indicate its time for some maintenance
. They are spring loaded so maybe a spring is getting weak or the return of the piston is sticking then releasing with a clunk. I dont know for sure.
Seastar does not publish a service
manual for these pumps nor sell internal parts
to consumers except for a seal kit. Are you anywhere that its feasible to find a Seastar tech?
How old is the pump
The slippage of the helm is likely a check valve issue. It is normal for a hydraulic helm to continue to turn under firm pressure, but you can hear/feel the check valve repeatedly releasing pressure. How much force are you applying in the video?
Slippage could also indicate air in the system or a fluid leak.