You might check to see if there is a kink in the plastic gas line hose. The front heater worked the first few times and suddenly stopped working. Went through all the trouble shooting stuff I could find. When I pulled the vent on the front of the bath sink the tubing did not look right but really could not see it very well. I pulled the heater partially out and, lo and behold the line was kinked. Looks like it took it awhile to totally shut off the gas. Replaced the line and it worked fine. Looks like it was kinked during installation.
Dawn and Mark
06 HR Endeavor 40 PET