Mamiya 645AFD focus stuck in manual

I have a Mamiya 645AFD that hasn’t been used in several years. Today I decided to put it to work again. Fresh batteries, etc. However, I immediately encountered a problem. The camera is stuck in manual focus even when the focus mode selector is set to S or C. At first I thought it might be the mounted lens so I switched lenses. Same thing. I investigated further. First, I checked the focus on a couple of lenses by using a small screwdriver to operate the focus receiver on the lenses. They all turn smoothly and move the focus ring. Next I examined the focus driver on the camera. It pops in and out just fine. Then I determined that the driver and receiver are engaging correctly by turning the focus ring on a lens mounted on the camera v. not mounted. Not mounted the focus ring turns freely, mounted there is drag. That proves engagement. Also, when depressing the shutter release you can hear the focus motor operate for a second or so. Is there anything else I might try short of sending it out for expensive repair?

Ideas appreciated.

Larry

Haven't gotten any feedback here so I thought I'd add to the original posting. With not much else to chose from I decided to do a little more exploring on my own. Managed to take the critical parts of the outer body off to get to the mechanism and electronics. So, the focus selector on the front of the camera body seems to have both a mechanical and an electrical function. When M focus is selected it withdraws the little screwdriver type device that engages the focus on the lens. However, although I can hear the focus motor run when the camera fires, the gears indicated by the red arrows don't turn.