My 39 year-old autopilot (Bendix FCS810) that was declared dead by several shops, was overhauled and repaired by a shop in Edmonton, Canada. After re-installation, all pots on the computer and control panel were soaked in Corrosion-X
No more troubles since at least 10 years, works perfectly.
On these old analog autopilots, the pots going scratchy are probably 75% of the problems. Worth giving it a try. Don't allow any Corrosion-X to touch any of the clutches on the servos. Treat all connectors and pots and circuit board connectors you can get hold of.