Camera stuck in autofocus, switch problem

Hi, I wonder if anyone can help. I have recently purchased a used K100 Super which worked perfectly when I bought it. Since then a problem has occurred with the AF/MF focus switch which is stuck in the Manual position, but the camera working in autofocus. I have tried removing lenses, turning camera on and off at the same time, but to no avail as the switch will not slide. Before I take the next step and contact Pentax to get it repaired, which I imagine will be costly, has anybody had any experience of this and can offer a solution.
Many thanks

It sounds to that the switch is physically stuck. It operates the autofocus drive pin which is between 4 and 5 o'clock on the lens mount. In MF mode the pin is retracted. It might worth seeing if you can gently push it back in.

You may well find that it will cost more to repair than the cost of the camera! You might want to get a quote from an independent first (see here).

The link is, as gartmore states, mechanical. Did you bang the pin at some point?

Thanks for your help. i have tried the pin and it moves freely. I have exerted pressure on the switch at the same time and it remains stuck. I think the problem is internal and i will have to seek out a repairer.
many thanks anyway.

Hi thanks for your reply. No i have not touched the pin, but what may have happened was that I was using the camera as i thought in Manual focus when in fact it was in auto, and pressed shutter release whilst still moving the focus ring for the fleetest moment. I will contact the independent I think.