Lost reverse, need help finding it. 727

My very low mileage 727 lost almost all reverse . tried to take it out of the garage on father's day. Started backing out of garage and everything seemed ok, had to pull back in to get the angle right to get past the tree. Put in reverse again and it seemed to be slipping, really had to rev it up to get it moving. Pulled forward again and it goes forward just fine. Tried reverse again and its getting worse. Pulled it in checked fluid and thats fine, nice color and no burnt smell. Let it sit a week or so and drained the fluid, pulled the pan .No clutch material in bottom of pan, just a little drag residue in the bottom of pan.
Checked reverse band adjustment and it was fine.
Where Do I go from here. Pop the reverse servo out?
Everything was fine about 2 months ago when i had it up and down the driveway a few times.
727. Had new clutches, and bands performance, don't remember brand they have been in quite a few years. But it only has a few passes down the strip and probably less than 100 miles on it. Also has a reverse manual cheetah valve body, 4000 stall converter , and a deep pan with filter extension.
Need help finding reverse.