Thanks Robert. Ignitor seems to be doing its thing...glows and ignites the gas, remains that way for a little bit afte flame is present. I'll try cleaning the sensor.
Think it's just coincidence that seems to work properly with the cabinet door open?

I have Nordyne model G5RA096C-20, serial # G5R9506-00137. My problem is that in heat mode, flame is (occaisionally) shutting down after a few seconds of burn. Sometimes remains lit on retry, sometimes not. I've checked/cleaned entire vent, removed and cleaned venturi(s), removed and vacuumed at draf...