[Richard]

I think Steve has given good advice. If that does not fix the issue, then some sleuthing is involved.

Before sending you into a potentially hazardous situation please answer the following.

Do you have a voltmeter and know how to use it to measure 120 Volts AC?

Are you comfortable with exposed 240V ? Because one of the steps will involve removing the cover to the transfer switch.

And to answer your question, it’s not bad at all.