Autohelm ST7000 knocking sound

[FecklessDolphin]

While sailing in a gentle downwind situation I noticed a slight knocking sound coming from the drive unit of my Autohelm ST7000. The sound had a "boing" quality to it and at first I wondered if it could be hitting a fender buried in the lazarette so I cleared everything out of both lazarettes and watched it. The unit was moving in quick, 1-2mm increments, making minor course corrections in both directions. Some previous postings on this site suggested a hydraulic issue and suggest checking the resevoir and bleeding the unit. That discussion, however, pertained to a cat and I am not clear if the same thoughts apply to my 36' boat. I have to travel to get to the boat and I would like to be prepared to go through a trouble-shooting list next time I am there. Any suggestions?

[DayDream]

I had a knocking sound on my ST7000 unit- I have a chain drive through a Whitlock pedestal. The drive motor had loosened up on the mount and was clunking when it changed direction. I tightened the chain then tightened the bolts- and it was fixed.
Maybe that will help?

[Wind Shadow]

Hello, I am in serious need of a 12 volt drive motor (any condition). The motor is for the linear drive for a Autohelm 7000 autopilot. If anyone has one sitting around that you don't need I would appreciate it very much.

[Mystic38]

what type of drive unit do you have?.. my linear drive exhibited exactly the same problem.. it was excess wear due to misalignment of the rudder bearings.

Although i swapped it out, Raymarine can refurbish them (if you have the time to wait)