Discovered the root cause of the tilt mechanism not working...
Someone had the bright idea of putting a sheetmetal screw in the clutch assembly. They removed the bellville tensioning springs, snap rings, etc as well. I'll have to source quite a few parts for the entire tilt system. The hammer blow coupler and/or worm shaft are broken.
After some troubleshooting it appears that the SelectTrim motor is dead.
Looks like I'll have to do some disassembly of each system and go from there.