so I installed my new clutch and fly wheel today at the hobby shop. when i tried to to put the car in gear with the engine running it would not go but it would go into gear with engine off . So we bled the clutch and tried again. Again nothing. So we raised it on a lift and started it while it was in gear. It made a loud screeching noise. so i shut the car off. I started again in neutral and then put it in gear with no problems. Any suggestions on whatcould of caused this?

 

not a pro at manuals but maybe syncros?