Hey there! I have a 2004 Avenger. It failed last march and I rebuilt myself it soon after. I didn't get it quite right. I believe the fix is fairly easy. What is happening is when I shift from F to R the shift knob will lock. What I believe is happening is that the Block shift is catching the Fork shift and moving it backward just a little which restricts the shift lever from switching grooves to engage the reverse gear. When I rebuilt the transmission my old fork shift was fine but I replaced it anyways as I was already in there. The new fork shift was quite tight to the Block shift but I stayed with it and sealed it up. It runs great with the exception of locking up occasionally. I am able to quickly remedy it by removing the plate shifter (where the Knob shift enters the transmission) and putting a screwdriver into the fork shift and manually putting into where neutral would be. (about a 2 minute fix) it will then be able to move gears. I am about to open it up again and have at it but was looking for some guidance if anyone here knows what I have explained. Thanks for any tips in advance. This machine has turned me into a mechanic. I rebuilt the engine last year and I have now removed and reassembled 98% of the bolts on this machine.