I have an old Yamaha 2600 watt generator. When I bought it years ago it was
awesome. I was even able to run my compressor off of it in a pinch. It was
clean too. Computers TVs. No issue. I haven't fired it up in several
years, but last year we had a power failure at the house for 3/4 day, and I
tried to run our fridge off of it, The fridge never started. It ran lights
just fine. and I was able to run my table saw or my band saw, but they just
didn't sound right. I pulled out my old Radio Shack meter flipped it to
frequency mode and checked it. Yep 400 hz. This meter very reliabley shows
household 110 at 59-60 so I know its not out in left field.

Where do I start looking to fix the generator?