fishinjunky wrote:It starts working again after someone rocks the chair.
I would use that fact and audibly tracking the noise source to start investigating.
What is electrically related to tilt, and moves when you rock the chair manually?
The position feedback component inside the actuator is one such thing. If it is based on a conductive track like a potentiometer, it is subject to wear. Wear would happen most around the tilt position you occupy most. Check if the problem also exists at non typical parts of the tilt range. If not, use those positions more often till you can get the actuator replaced. If pot wear is the problem, the click would be a relay disconnecting because the controller inside the actuator sensed an invalid position when the wiper passed over an open part of the track.
Limit(overtravel) switches could be at fault if the problem only occurs near the ends of actuator travel rather than the most occupied spots.
Connecting wires also move when the chair is rocked. Potentially breaking/making a contact.