Fist off the gearbox is from a Hydro 00' JDM Civic Type R. It came with a 4.4 FD but I swapped and sold that for an Mfactory 4.785, and I now I took that out and sold it and purchased a GSR 4.4 FD from a fella on here. I went back 4.4 because I am boosting the car. So now I was putting everything back together along with a new set of Synchro tech 1-2 & 3-4 carbon synchros, but the damn mainshaft will not turn when you bench shift it into gear. When I took a screwdriver and tried to manual shift it at first, it wouldn't shift, but after a little shaking it started to shift. In 1st and 2nd the mainshaft spins freely, in 3rd and 4th it spins then tightens up, in reverse it spins freely like 1-2, but in 5th the shaft locked up completely and doesn't spin an inch. Oh, it spins freely in neutral also. I took it to two separate mechanics who took the whole assembly apart and still had the exact same problem! What could this be??? It has me totally stumped. Ant input is greatly appreciated.

 

bump for any kind of ideas.