Curious, what oil did you fill it with ? The statement that it doesnt grind, just wont go in and then if you clutch & rev it you can get it in desired gear is very telling. I have an sm420, syncro's in 3rd & 4th and I can downshift, just have to be in the right rpm. If it isnt grinding & just wont go in, I have a ? does it come out of current gear and wont go into lower gear , stuck in Nuet. ?, or does it not come out of current gear ? I ask because IMO if it is not coming out of gear at speed its the clutch not releasing all the way. Experts please review the pics, is the 1,2 synchro in backwards ?