Onan 4000 Generator won't turn over some of the time

I found out the hard way that it is important to remove the load from the generator and let it continue run for a few minutes to cool down before shutting down. One time last trip we shut the generator down immediately after turning off the air conditioner and the next time we tried to start it was seized. Luckily a ratchet wrench on the cooling fan broke it loose and it has been OK since.

I have seen posts about the top dead center issue, but never experienced that.