Toshiba G7 vfd

So, here's the deal. I have a deck chain with a 5 HP motor attached to it. I have a foot pedal to stop/stop and an adjustable pot for the operator to use. So....... When the operator hits the pedal to start, the chain 'creeps' forward for about half an inch to 2 inches then starts 'creeping' backwards for a couple inches. I do not have a reverse on this chain setup at all. Is my vfd on its way out?

I'm not 100% sure I have this straight in my head. Could you explain the proper operation of the chain, and then what is actually happening?

I assume that this system has worked normally for some time and that this behavior had never occurred until recently?

Does it make any difference when the speed setting on the potentiometer is changed? Have you checked the voltage at your drive's speed reference input terminals while having the operator vary the position of the potentiometer?

Have a look at this thread:
http://www.plctalk.net/qanda/showthread.php?t=90573&page=3

The flying start setting was causing a similar issue.

EDIT: gosh - I didn't realize this thread was on a Toshiba drive. Sorry if the reference thread has no bearing on your problem.