Is getting stuck sometimes. Arrgh.

It seems to be typically with one back. I've tried it on both my camera bodies, and it seems to be happening more frequently. It has also happened with one of my 220 backs.

Anyone else have a similar issue? I think it must be that the electronics that "talk" between the camera and the back are not quite connected. Any thoughts or ideas about how to make sure everything is properly attached and speaking to each other... or should I send it to the Mamiya ER???