OK, this was my first roll of film through my Nikon FE, so I'm not sure if I'm just missing something or what.

First, I will say when I loaded the film, I had a hard time popping the knob and getting the back open. I pretty much forgot about it after that (been a month or two).

Yesterday I used up the roll...I assume...it got to 36 on the counter, and after what would be 37, it made a different sound when I wound it. When I went to rewind the film (yes, I pushed the button on the bottom), it started off seeming like it was winding, but very quickly turned without resistance (as in, probably just a couple revolutions, not enough to have rewound the film). I re-read the manual to see if I was missing something, but I don't see anything. Somewhere online it said to pull the knob up slightly (not enough to open the back) and turn in that position. Well, the knob won't pull up at all. I've moved the little locking lever counterclockwise as far as it goes, and still it won't budge.

Am I missing something? I'll admit I'm still relatively new to 35mm SLR's, having only shot a few rolls on my previous Canon AE-1 Program (one roll that I had a hard time rewinding on it...but it was missing the lever completely) before switching to the FE.

Just as added info: this was an ebay FE, which was listed as good used condition, and I believe "not tested." It had a dead battery when I got it and so the shutter wouldn't fire except in B and M90, with new batteries the shutter & meter seemed to be working fine through the roll. I'm thinking when I loaded the film I also had a problem opening the back, despite following all instructions, and it eventually (and for no good reason that I remember) just finally opened as it should.