My Thermador gas oven PG366BS has been getting flakier to start up. The broiler works fine, it's the Bake or Convection Bake that's the issue. Sometimes nothing happens, sometimes it starts briefly and I get a little heat and then it stop, and sometimes it works normally. I thought at first it might be a faulty igniter, but when the igniter doesn't work, neither does the gas. So now I'm suspecting something further "upstream". Maybe the temperature sensor? or some other control module or circuit board?

Can anyone advise how to reach any firm conclusions before I go start buying random parts?

Thanks!

L