Norman Valentine , Oct 28, 2008; 04:57 p.m.
I used to have a K1000 with a similar problem and used to free it by banging it as hard as I could onto the "heel" of my hand. This did not do the bottom plate much good (it still has the impression of the insides on it) but enventually I realised the problem was caused by the release button being bent over from contact with a wall on a drunken trip down the stairs! I straightened it with a can opener. Nothing technical but it does say a lot for the strength of this camera. I hope your cure will be as simple.