Had same problem in my buddy's trans. Took trans apart and could see nothing wrong, all new stuff. Then took apart vb and found rust and old black fluid and grit. The man who rebuilt it never cleaned the vb, just stuck it in. I did put anouther vb in and same thing again, was going to pull trans apart again but I'll check the vb first. Thanks for the help, by the way, the part throttle kick down had the rust in it, locked up, reason for the other vb.