Everything turns but the output shaft

[Coblue]

Newbie here, great site for someone looking to keep old Warriors running!
My output shaft on my'87 no longer turns with the transmission. I removed both side covers, and everything I can see seems to be working. It seems to shift gears fine, but the output shaft doesn't turn. I'm getting ready to split the case, anything I should check first?
What commonly fails that would cause this?
TIA!

 

[Gen1Pat]

Sounds like you have worn teeth on the shaft or the gear it meshes with. Any abnormal noise or metal chunks in the oil?

 

[Coblue]

Nothing unusual so far in the teardown. I wasn't there when it broke, so I don't have any background either.

 

[Coblue]

So I split the case last night. Nothing appeared broken, no major debris or shavings. My guess is that the reverse selector dogs were not engaging because they were sliding on/turning with the web face of the gears and not dropping into the gear pockets to engage the gear. They will engage when the positioning lines up. Any suggestions before I put it back together?