About 3 months ago our upper oven would not start unless we ignited a surface burner. Now the lower oven is doing the same thing and the upper oven does not work at all, broil works normally. The hot-plate ignitors are glowing, just gas valves do not seem to open. In looking at the wiring diagrams, my thought is that the problem relates to the control board, but wanted to get another opinion.

Thanks

It ended up being the ignitors. As the ignitors age they take longer and longer to light the oven. In this case the activation of the burners was enought to open the gas valves to the ovens even wit the reduced current from the ignitors. The other indication of the ignitors needing to be replaced is the oven reach temp. then does not re-light to maintain set-point.