I started the tear down my 175 after I found out 3rd gear was gone. I got the motor out and was disassembling. Couple findings...
The oil filter rotor: If I would have looked at the manual first I would have known the cover was just pushed on. Instead I tried to use a screwdriver on it and spin it (kind of like the way hubs are). I broke off the remaining tab (someone already broke the other one) before I realized you just grab it with pliers and pop it off. No real harm done, you can reach into it with a awl type tool and pull it off.
Once inside the filter rotor I found metal flakes. No real surprise with the transmission acting up but isn't there supposed to be a filter in there?
The last worry is that bolt inside it. Anyone have any ingenious ideas on getting it out?
Oh, and dig the weird scratches on the clutch housing...