Where i work we have an International 7400 DT530 6 speed Allison auto. We recently had some electrical issues with it, we kind of figured that out. Ever since those issues became serious and not so intermittent, as it had been for a decade, the exhaust brake would sometimes stutter. When the electrical issue became more serious the brake stopped working altogether. We basically fixed the electrical issue, but now the exhaust brake does not work at all. We have checked all fuses, we have swapped and replaced relays, and tested the actuator itself on the turbo which moves with ease, to no avail. The odd part is, when driving with the switch turned on for the brake, the transmission still downshifts as it does normally when the exhaust brake is working properly. It makes me think that something inside that housing is busted off or frozen, and the electrical issues happening around the same time are just coincidental. Any input or help would be appreciated.