Ricoh 500G shutter release sticks

[Evildmp]

The shutter release on my Ricoh 500G, which has worked flawlessly, has suddenly started jamming.

When I depress it I can feel some friction in the mechanism. To get it to spring back up, I need to lift up the button past the sticking point.

This happened suddenly, without warning signs. Is this a known problem?

Thanks.