Had a misfortune with my auto pilot this weekend on my "ST4000 tiller drive", accidently stepped on it while on a 40 deg heel and it seperated at the body joint and as a result broke the "gear Anulus".
for older model products at Raymarine
seem to be non existant, hoping that someone out there has an ST4000 unit not working and/or colecting dust or just upgraded and looking to sell their old unit.
The Anulus is just a plastic housing where the gear
wheels revolve kind of like a sun ring in a gear