get a digital meter and check the voltage at no load idle and then again when you turn on the pot, and again with the MW
I think your problem is the coffee maker, not the generator, the voltage test will give us clues, i'm guessing NEWer pot with digital controls, and something in the coffee maker doesn't like the wave form from the generator or the NO load frequency , and when a load is applied the coffee maker controls come on
if voltage is too low or high, idle can be adjusted, or the governor adjusted for the correct RPM
