Long time reader, first time poster............ I tried the fail proof way of unlocking a 641 transmission, by backing the engine up and got the transmission free and all shifters appear to work as designed & work properly. However when I put the top cover back on and fire the engine with clutch disengaged I am able to shift through all gears smoothly but if I start to engage the clutch the motor starts to bog down no matter what gear that its in, including neutral. My conclusion is that there is still something locked up / broke. I have heard no pops or bangs and everything looks OK, but; I still have a locked up problem. PLEASE HELP......ta