Suggestions - 25mm problem

My 25 mm f2.8 had been working perfectly until a few days ago.  It refuses to focus beyond a metre, instead making a slow clicking noise.  The same happens if I switch to manual focus.  The lens barrel does not seem to fully retract when I switch the camera off.

Before I make a warranty claim, I thought I would check here for suggestions as to possible cures. I have tried re- seating the lens and cleaning the contacts.