I have a 1985 Cherokee pioneer 2.5L 4cyl with the cda904hd transmission in it.

My question is, the Jeep runs great, shifts fine in forward gears and shifts seamlessly between them.
The reverse seems to have an intermittent issue with just not engaging at all at times. It's weird, and I understand that it's a nearly 40 year old vehicle but I've checked the fluid and it looks clean and smells as it should and can't seem to figure out the issue.
Anyone have any tips or knowledge about this old of a setup or anything I could try or a place to even source a transmission for it???? Help me please!!!

 

How long since a fluid and filter change?

 

The A904 has adjustable bands, and I *think* there is one specific to reverse. Google for you youtubes or guides on adjusting those bands when you pull the pan to do a fluid/filter change.