I haven't looked for a guide Nick, but I'd check that the mount thread looks good (no evidence of cross-threading), the VF is in good nick and the RF aligns properly, and the slow speeds sound OK. I'm assuming it came with the take-up spool?
Shine a torch on the shutter curtains and put a test roll through to check for pinholes in the curtains.
I bought a user IIIc and am very happy with it. They are nice cameras, very tactile. The shutter should sound with a quiet "snick".
My Summar #388XXX has a regular hexagon at all apertures. BTW I can recommend "ROR Residual Oil Remover" for cleaning lens elements. Scott at Mainline put me onto it and it works a treat.