I have a weatherman 8000 furnace. In using it this winter it has become necessary to continually reset the safety switch which is held in by the furnace door. Because I have to do it so often I have now taken the door off and taped the switch in place. Even with it held in however I still have to let it out periodically through out the day then retape it in position. What can I do to help this and what is wrong with it