Don't be fooled by people telling you to disassemble the bolt for cleaning. Putting it back together is a bear to say the least. My opinion is that wasn't ever meant to be disassembled by the user. Soak the bolt in cleaning solvent if it seems sticky inside. Many folks wish they had listened to this advice.
Numerich e-gun parts is probably one of the only places you'll find parts other than folks selling on e-bay. Finding one on e-bay that can be a parts doner might also be an idea even if it is incomplete.
I have a 1937 Rem. 341 Sportsmaster and a 1942 Rem. 512 Sportsmaster. Both are excellent rifles to shoot. They are very accurate. The old 341 is probably superior to the later models. I think the "41" series guns were still being made by hand by skilled gunsmiths where the 5-teen series guns of a few years later were mass produced by factory workers.