Well, carp. I was load testing the generator tonight - everything was looking good - ran at 50 percent for a half hour or so, went to 75 percent and blew the head gasket. UGH. Hopefully it won't be needed for these next few storms. Good news is it looks to be a fairly simple job (as compared to many other engine designs). Time to order parts, get out the TM's, and read other's head gasket stories. At least it chose to go out during a test and not an event. It ran flawlessly for several days during Irma.