727 no reverse, forward in neutral after rebuild

I know its a year later but did you ever figure out what the problem was?

This exact thing is happening to mine. 727 bb, rmvb from turbo action. For a long time wont go into neutral when running unless been driving for a while. If you try when not warm enough it makes grinding/buzzing gear noise (real faint but car is loud). Reverse used to work fince once car warm but now no reverse cold or warm. Forward 1-3 engage but havent driven down road so dont know if working fine while driving. Car will go forward with a little gas if you put the shifter between park and reverse...reverse wheels feel locked. Park sometimes wants to initially jump forward a bit then locks into place. Had pan off and fluid looked good with normal limited amount of very fine metal residue in it....low/rev servo spring etc all in place and adjusted to 2 turns out. Didn't check other band. I also didnt pull the servo out so maybe it has a crack or something? I haven't done any air testing or pressure tests at this point. It started doing this after I had up in air (sometimes front end only) replacing all brake components and front shocks.