I have a gsr transmission that won't go into first unless I put it in reverse roll back then it can go into first. It's comes out just fine when going through gears even at 8500rpms but once it's out it won't go back in. Does anyone know what the problem could be?

 

Thinking that the stoppers on the synchro may be damaged. This causes the teeth to align on top of one another and prevent engagement.