billeboy

I'm helping a friend resurrect a 1975 Dodge Travco motor home and it presently has no reverse. The transmission is a 727 Torqueflite, all of the forward gears work but absolutely no reverse when the shifter is placed in the "R" position. Here is what I've done in an effort to fix:
1) I've pulled the valve body and inspected the reverse band, it is intact with no apparent issues.
2) I've adjusted the reverse band per specifications.
3) I've injected compressed air into the hole next to the reverse servo and the piston moves freely.
I'm thinking the problem must be upstream of the servo and quite possibly within the valve body. Any ideas or thoughts? Thanks!