Having issues with a couple of these boxes. Can't seem to get the vavs to respond properly to a change at the zone sensor or the tracer touchscreen. I have replaced the pressure transducer and cleaned the pickup rings. If I drive the damper from the tracer panel, the vav starts opening for a minute or so and then stops. I have checked the end switches on the damper assembly. I'm about to change the board as I can find nothing else that canned wrong. Any help would be appreciated.