the light seems not as bright as it used to be.
You may have a poor ground for the igniter. Disconnect the power wire at the plug then loosen and retighten the igniter assembly. Reconnect the power and check the brightness of the glow plug.
From Bigbear
I always shut off my make up gas when igniting.
Good advice. My ignition procedure is to shut off the hydrogen and makeup gas flows then hold down the ignitor button while I open the hydrogen valve. Once the flame is lit (monitoring the signal on the GC display), I open the makeup valve.