Power to AC's on Generator

Sir, this is my 2 cents worth on this issue. You have two contactors in your transfer sw. one for shore power to coach and one for gen power to coach. When you go to gen power the shore power contactor opend and then the gen power contactor closes. In those contactors there are two sets on contacts, one for each leg. It sounds like only one set of contacts in the gen contactor is closing or has forgien mater in them. The only way to know for sure is to put you r meter on them while gen is running to see if both have power on output side of the contactor. If not then the contactor needs to be opened with all power OFF and I mean all power, both shore and gen, to see what is going on. They are serviceable and replaceable individually, you just have to know how. Good luck.