trouble Atwood cooktop

If none of the other suggestions work, spray down the valves and gas manifold and so forth with bubble solution while the burner is on and inspect for bubbles indicating a leak. I currently have an oven control valve that leaks from the valve body when on and with similarly spectacular (and dangerous) results.

There is an asbestos 'gasket' that sits on a flange at the top of the gas tube. On this one tube, about 1/3 of that gasket is broken and laying in the 'pan' of the cooktop. This may be allowing some gas build-up even while the flame is burning and then the gas builds up enough to POOOF a flame out the front? Had the coach checked at CW in Anniston, AL. The tech didn't think the gasket was a big deal, but then he didn't think a number of items were 'big deals'..

Check the alignment of the orifice and the ventury tube. Sound like its misaligned and flashing back to the orifice.

Pop the top off so you can see the tubes going out to each burner and the wires from the sparker etc. Poke things if nothing obvious.