My 90 GL will no longer shift properly, that is, it will start out in bottom gear, shift to intermediate, but will not go into top unless I put her into neutral, then back to drive.  It does this only when fully warmed up.  Another thing is , when it is warmed, is it will not reverse, unless I put it into R, wait, and then rev the engine.  The fluid level is proper, red in colour, and no burnt smell.  A while ago, I had it rebuilt, and ti had the same symptoms, but it self resolved.  The rebuilder said he tried to adjust the selector at the valve body, but could not.  (When I first picked it up, reverse gear stayed engaged whilst in park).  My question is, can the linkage be adjusted anywhere else?  I hate to face another rebuild.