What a find!
Roaming through an antiques mall the other day, I saw a beat up tan leather case with a Nikon logo on the front. The tag said "Vintage Nikon 35mm Camera, Case, Light meter." I'm thinking "cool! it's probably an old F or maybe F2." My heart about stopped when I opened the case and saw a Nikon SP in great condition. It has a W-Nikkor.C 2.8cm 1:3.5 lens attached.
So now I'm the proud owner of a Nikon rangefinder. From what I can tell, everything works beautifully. The shutter speeds from 1s-1/30 all sound like they're properly timed. There are no odd sounds or anything. Film transport is all working. The rangefinder works. There's a black yarn-looking light seal along the top edge of the camera where the back slots in, but no seals I can see on the sides or bottom. I'm assuming this is normal.
Anything else I should check out before I toss a roll in it and give it the ultimate test?