Dealing with the parity lamp dimness issue

OBSERVED BEHAVIOR OF THE PARITY LAMP

When a parity error is detected the lamp should illuminate brightly but was very dim the last times I had a parity error. Possibilities are that the driving input to the gate on the 3819 card is not at a valid voltage level, or the card is defective in the circuit for this output, or there is something wrong from the output of the 3819 to the lamp. 

TRACING DOWN THE SOURCE OF THE ISSUE

I quickly discovered that the bulb itself was bad - an open circuit. I replaced the bulb and verified that I got normal brightness with a parity error. 

However, after doing some other testing on the machine I noticed that the bulb was glowing dimly, just like before. 

This circuit is unique in having a capacitor across the input to the driver card (3819), a 0.22uf 100V component. If the part is leaky and acting a bit like a resistor, it would pull down the +3V output of the signal source gate. I am going to replace it and expect this will resolve the issue; if not I will keep working at the problem.