Exhaust brake question: I often tow my 38' fiver in hilly/steep country. I always have the exhaust brake active when towing--and it definitely helps slow the train down as expected and necessary. But in many instances, it won't let go when I want it to. For example, last week as we were coming down a 6% grade that had a few curves, it engaged when it should have, and held me safely back as expected. But when the road straightened out near the bottom of the grade, I wanted to let it coast a bit to return to normal speed. I tried turning off the exhaust brake switch--but that did nothing. I tried accelerating--it continued to hold on. It finally released after 30-45 seconds at just over 4k rpm. This behavior pretty consistent. Is this normal? Is there a trick to getting the brake to let go when I want it to?