Just got a Minolta XD7 off ebay and I'm not sure if it has a problem with the wind on mechanism or not. When I load the film it winds on for a frame, I release the shutter, then it seems to stop winding. The lever can be operated but the film won't wind. However, when I close the camera back and wind on after a few strokes the rewind crank starts turning and the film safe load indicator seems to work ok. Is this normal? The seller's offered a refund but obviously I'd like to keep the camera if it works.