picked up a older pdv today from a guy who said it wouldnt run hot enough. i figured no problem i would give it a good cleaning and all would be good. well i gave it a good cleaning and even on 9-9 its not blowing hot. the bottom 3 are 4-6-1. this was done in my drive way with no vent or oak. and the results were after about a half hour of run time. what should i look for?