I worked on tearing down the transmission some more tonight. Here's what it looks like now:
The clutches, brakes and carriers
The pump. Everything came apart with a few easy blows with a plastic faced hammer, except for the bearing you see. I pressed that out using a 3/4" drive 1 1/8 socket. It was close to a perfect fit for the task.
Solenoids
Main valve body
Main plate. This thing is very nasty as seen by the dark surface
Pair of roller bearings that look to be in excellent shape
Now both planetary gears have these grooves in them. I *think* that's normal given how even they are across all 4 gears in both units.
Here's the output ball bearing. I need to pick up some "real" snap ring pliers to get these out. The assortment of what I currently have aren't up to the task.
So with the transmission almost completely torn down at this point, I haven't really come across anything obvious that would explain the failsafe message I was getting. Maybe as I complete the disassembly of the valve bodies I'll discover something, or maybe once I complete taking the carriers apart?