Disconnect the wire harness from the bake and/or broil igniter. Program a cycle. and check for 120 VAC in the connector from the cabinet wire harness for the igniter. If you have the voltge, you’ll need to check for 3.2 to 3.6 VAC at the burner valve, across the wires that come from the igniter to the valve. Low or no voltage at the gas valve terminals, would indicate a weak or broken igniter, and the switch will not open to release the gas and ignite.