FS-534 Main Tray Won't Rise

[bearyb]

I've got a C654 with a FS-534/SD finisher where the main tray goes all the way down to the Main tray full sensor flag and stops. It will not rise back up at all.

The springs on the Surface Sensor claws are intact, and in Sensor Check mode they do change state when I lift them manually ("0" when down, "1" when lifted), as does the Main tray full sensor. Normally, raising either the rear or front set of claws manually while the main tray descends will stop the descent and start the tray moving up again. This tray just keeps going down regardless. Once it hits the Main tray full sensor (or if you trip it manually) the claws will raise and lower once, and then it's done. Nothing else happens.

No codes have been displayed, only a message to unload the paper tray.
I loaded the latest firmware (G00-72).
I've swapped both the FSCB and the cover (that has the claws and sensors attached) from a working finisher, to no effect.
There seems to be no Load Check available for the Main Tray up/down motor (M11).

The harness connects with J14 on the FSCB. Maybe a bad harness?

Any ideas would be appreciated