Some time ago I posted a query about a 205 door lock jamming at irregular intervals. I eventually found the cause, if anyone's interested:
There is a lever on the back of the catch mechanism which is linked to the outside door handle by a length of wire. This lever occasionally sticks in the up position & refuses to drop back, which stops the other lever connected to the lock barrel from releasing the catch. Move this sticking lever back by hand, the lock works normally. Leave it, and sometimes it drops back by itself, sometimes it doesn't, depending (I suppose) on the time since the outer handle was used to lift it up & the amount of vibration shaking it back down.
Dave