Had to install a gas shutoff valve on the back of a direct-vent gas
fireplace (free-standing ornamental stove) to meet code but now the
main burner seems to be acting strange. Sometimes it goes out or
doesn't want to light. The pilot stays lit. I am wondering if some
dirt or rust might have been knocked loose and is now clogging the
internal workings. I tried to clean out the pipe with a Q-tip as I was
installing the valve but maybe there was still a bit of dirt left
inside. I'm not sure how I might be able to blow any such dirt out
with compressed air? Ideas?

Thanks