We purchased a used 2010 bighorn 3410 re with a eureka yellow jacket vac. I can't open the inlet below the stairs by the entry. The breaker is turned off and when I turn it on the unit runs and sucks in at the bottom. It looks like a door should open by swinging up as it looks like it has a hinge. It appears to be stuck so tight I'm afraid I will break it. Is there a trick to opening it?