I'd suggest checking ALL 120VAC connections in the breaker box AND Xfer switch while your at it.
Just BE CAREFUL. Even with genset NOT running and NOT plugged into shore power you can still find 120VAC if you have an inverter that's not shut down.
I found one loose connection in my 93 Pace Arrow Diesel Pushers 50AMP transfer switch. I was lucky it did not get too hot to cause damage.
Look over ALL connections for ANY discoloration. A loose connection can get VERY HOT. I had a treminal on one of the house batteries get so hot water sizzled when it hit the bad connection, that's on the 12VDC side!!
Again, be VERY CAREFUL! I'm alergic to high voltage and I bet others are as well.