A question about furnace gas valve replacement

[Marthe48]

4. The valve allows gas to release

to the flame, then? And flame/gas cancel each other out if one isn't working right?
The 1st repairman brought 2 troubleshooting devices in. The first one didn't pick up the problem, and after using the 2nd device, said that it was pretty definite that it was the valve. I think he said a solenoid was involved. He said sometimes you could tap on the valve to loosen it, but didn't want to try that. He shut the system down. Today, I stayed in the basement while he worked and heard the reassuring whoosh of gas lighting up.

My daughter thought it might be the capacitor, and remembering we've had them go out on furnace and a/c, hoped that was the problem, just because it was familiar

Thank you for adding information.