I'm hoping that diving into disassembly will allow stuff to free up but I have no way of knowing. So here goes nothing.
These steps I didn't get pics of but I removed the 4 bolts that hold the front input shaft bearing cover but have not tried to remove the cover. It doesn't hold anything in place so I'll save it for later.
I then removed the reverse shift lever retaining pin and pulled the shift lever out until it stopped. This disengages the shift fork from the reverse slider gear (or whatever it's called). There's also a pin underneath the shift lever that I believe goes through the reverse idler shaft. Looks just like the pin for the shift lever. So that came out also.
There are also two small bolts I removed on top that hold what I think is the center support.
I removed the 5 bolts that hold the tail housing to the main housing through the mid plate. Then I used a large screwdriver to carefully pry the tail housing off. Thankfully, nothing got hung up and it came off pretty easily. At this point the black mid plate is still retained by two bolts behind the reverse idler gear and possibly other stuff.
All of the gears here look fine. There are a bunch of these weird shavings. But they're not metal. I think it's some kind of foil with a paper backing that has shredded. It's adhered to the inside of the tail housing and it clearly made contact with the reverse gear. I think when the trans seized up, it flexed the case and moved the tail housing enough so this made contact with the gear.
The reverse gear is fine
The reverse idler gear slides off easily. It has several spacers and a bearing on each end. I removed these and tried to keep them in the order they came off and put them into a cup, however, looking at a parts diagram for a G-Force G-101 (closest approximation to a T101A), it looks like there should be two spacers rear most then the needle bearing then a spacer then the gear. I think when I pulled it off, the spacers and bearing slid off and fell on the bench. I picked them up and put them back on in the wrong order. Genius.
I removed the bolts behind it. I think they retain the black mid plate to the main housing.
Behind the idler gear, there is another spacer, needle bearing and spacer. The first spacer was stuck to the gear when I pulled it off.
Put the stuff in a cup with the rear most parts down. I didn't realize when I took this off that there is still a spacer on the shaft (see above).
The reverse slider gear just slides right off the shaft.
I labeled it so I'd know which way it goes on.
At this point I'm not sure where to go next. The mid plate still feels like it's being held in place. I'm not sure if it has anything to do with the item I have indicated below. I don't know what it is but it seems to go all the way from the rear of the housing to the front. There may also be a pressed in bearing that is holding it. The reverse gear has some snap rings I need to remove. I know that's also hold it in place but I'm not sure if there's anything else. Anyone have any ideas?