Reply to Broken classic?

As I've referenced in various posts I use two midi fighters with the instant grant + deckalised ABCD mapping routed to Decks A & B. Love it but having problems since going to TSP 2.6 (also use an F1)

Anyway;

One works, one doesn't. I've done the simple things like swapping them, swapping the usbs from the hub and direct connecting to the mbp and it's always the older unit that doesn't work.

MF utility updated, both units responding to the 09 July 2012 firmware.

Traktor does see both units and I assign as normal via device set up. However on the older MF I get no led's lit and the unit is totally unresponsive when you use it. The other one works 100% spot on.

Driving me mad trying to figure out whats wrong. Deckalised is the only way I use them, not interested in 4 banks mode so need both working.

The only reason I can come up with is the circuit card is bust, but if it was, surley MF utility would not be able to flash the unit? Any known issues with TSP 2.6?

Any helpful advice appreciated.