Sometimes my RZ wont wind on

Hi All, sometimes I find that my RZ pro doesnt want to wind on with the lever. The symptoms are that the lever does not allow me to go the whole way fwd and the lens remains uncocked.

I can usually get around this by pushng the the T lever on the lens a few times then returning it to its original position or removing the lens and cocking it manually.

It there a simple fix or a ghost in the machine? This happens maybe one in 30 shots.

Thanks

Paul