The big roaster has been down (got an email when I was at ICN on my way home). After rather a lot of troubleshooting I happened to notice that the wire going to the spark plug had fallen out, which would explain why the burners weren't lighting. Part ordered. Thankfully I'm in a zone where USPS is 1 day so if that ships out tomorrow I should get it Saturday with only slightly obscene shipping costs rather than private shippers wanting more than the part itself costs for next day.