No Status LED on Jaguar

[kjohnson]

I've searched around and found plenty of information about meanings for the status LEDs on Jaguars, but nothing about what could cause a Jaguar to display no LED.

Our situation:
Four individual CIMple Box gearboxes powered by one CIM each. One black Jaguar per CIM. We are using PWM instead of CAN and therefore have not attempted any firmware updates. Two of these Jaguars are KOP, the other two from AndyMark (all new in 2012).

Out of the box, all 4 Jaguars seemed to work. Our first real on the floor drive test was last night. We noticed with a tank drive program the two separate gearboxes running the left side were turning at slightly different speeds. Same with the right side. We chalked that up to brand new chain and gearboxes. After driving around a bit, going over the barrier and bridge a few times, we noticed all wheels were no longer being powered. Two Jaguars were still working properly, the other two are still receiving 12V but show no status LED. Even if PWM cables come loose and don't provide signal, the Jaguars should still show some sort of status LED.

What could cause a Jaguar to quit working and display no status LED after it was just properly running? Can anyone suggest what we could try to test these Jaguars further? I know Jaguars have a history of problems, should I just contact TI for an RMA?