Got the mainshaft broken down. The service manual says to press the gears and bearings off the shaft, but it all just fell off by hand for me, I hope that doesn’t indicate too much wear on the press fittings
Removed the shift arm attaching bolt and interlock guide bolt:
Pulled the mainshaft, countershaft, and all forks together:
This bearing is the culprit. It caused the scratching sound that instigated this whole rebuild:
Probably at my character limit, gonna end this post here.