Protemp 125btu kerosene torpedo/salamander heater. Fires with the cover open only, and I can close it , it will stay running. It will not start with the cover closed, hear the igniter, smell & see kerosene. Replaced the nozzle, replaced the air filters, checked the air pump vanes and clearance, getting 5 psi (spec) on the gauge, hoses clamped, fresh kerosene, tank filter clear, photo cell clean and jumped..... Any other suggestions appreciated...