Nordyne RL 90 will not start. Can see glow build in the ignition/flame chamber but then instead of blower starting, the unit would shut down instead. LED would blink I believe it was 3x (pressure switch was stuck closed) although I am not convinced it wasn't 4X. Pulled out switch, exercised it several times and then re-installed. All seems to work well. Would that likely be the problem or could there be something else yet that I need to be careful of?