Terry, MacDonalds used to be a Sunline dealer so I would expect they would be a bit familiar with the wiring. It sounds like you have only an AC problem not a converter problem. The top left section of the converter box is just an AC breaker panel like you would have in a house. (see pix below) If you remove the 2 screws holding the front panel you will see the wiring.
WARNING: Observe ALL safety precautions when working around live AC wiring.
You can try:
* reset the circuit breaker - turn it off then back on again, firmly.
* measure the 110 volts out of the circuit breaker at the screw terminal.
After unplugging the shore power cord:
* make sure the screw terminal holding the wire is tight at the breaker.
* check the wire at the back of the bathroom GFI outlet, it may have come loose. (note - RV outlets don't mount in a box like house outlets.)
* look for anything at the connections that looks nicked or broken.
If you are not comfortable working with AC and measuring voltages please ask someone that is. Above all, be safe.