The Stovebolt Site Forums The Shop Area Driveline 1937 three speed jumps out of gear

I have been asked to fix a gearbox, It was hard to get into second and would jump out of that gear.
I've pulled it apart , and another 3 g/boxes and everything is worn.
I find it hard to tell what actually causes this defect as I have no new parts to measure.
For example , what end float should there be on the main shaft?
How thick for the 2nd gear thrust washer?
Who might have new syncro hub / gears etc?
What else might cause it to come out of gear?

Thanks for your thoughts.