I just bought a used Vivitar 5600, and have a couple of questions. Is there a non-dedicated (single contact) module available for the Vivitar 5600/5200? These flash units take the "PM" (processor module) series. Also, I noticed that due to the recessed locking knob design, it's hard to tighten and loosen the flash unit. I can't get my fingers in there easily. I was thinking of filing away a bit of plastic near the base to make it easier. Am I missing something? I may have to modify both the contacts and the plastic near the locking knob on a processor module to achieve what I need (single pin operation and secure coupling to the camera). Thanks.