Looking for generator repair advice...
I have a Winco 900-watt Tri-Fuel generator with about 320 hours on it for
home standby use. It's worked well for years - it easily powers everything
in the house except the central AC. During a power outage last night, after
it had been running for about five hours, I turned on the basement light
switch, the lights flashed momentarily and then went out. The only other
load in the basement is a dehumidifier that I always keep running when on
generator power as it helps stabilize the output. I then found that the
breaker for the basement had tripped. We've been in the house over 20 years
and I've never seen that breaker trip. I reset the breaker and then the
entire house went dark. The generator kept right on running with no
noticeable change in sound (i.e. it didn't sound like it was working harder
or easing up). I tried resetting the breakers on the generator, plugged a
light into the outlets on the generator panel - but nothing worked. I turned
it off for a while to see if maybe the problem was heat-related. Still no
luck. It starts up just fine but produces no power. It seems unlikely that
the problem would be a loss of residual magnetism. It gets exercised
regularly, and it was running for five hours when it failed. Does anyone
have any suggestions for things to look for?

btw: After the main power came on, I turned on the breaker for the basement
and everything functioned normally.

tia