RE: OS 90 4 cycle repair
The reason it broke is that it's a left handed thread. Now you need a new camshaft and that little impossible to find lefthand screw.
Changing bearings in the old OS four cycles (60, 75, 80 and 90) is a lot more difficult than in the new oS engines. There are five bearings and the front cam bearing is an oddball 15x20mm stainless steel bearing.
Those parts are going to be a B---ch to find. Any parts for the OSFS90 are going to be hard to find. Lee doesn't carry parts to repair engines.
I have severel boxes of parts for old OS 4 cycles. Give me an email and I'll see what I can do for you.
Bruce
Yeah that guy, BL