Interesting.....I wasn't aware that there was a different heater for the '54-551st. There is definately a vent/door of some kind; I'm sure that it is what's hanging up the whole mess. I tried again tonight, but it just won't move any more than 1/4". Guess I'll try spraying some PB Blaster through the cowl louvers. At this point, I'm ready to try anything.....
