Just to be clear - the genset ran fine for a couple of days after the fuse replacement. I am not convinced the two problems are related. I was hoping the prior failure was due to an 11 year old fuse just failing in light of time, high heat and vibration. Furthermore, given that the recommended replacement was 10 amp, i figured that must be on ongoing problem. I am certainly not a fan of installing large breakers or fuses or safety systems to short cut the proper cure another problem.

What I will do next time I am out at the barn though is put an 8 amp back in and see if it fries. If so, that may be the start of where to looking for the problem. I spent some time with it yesterday and of course couldn't get it to mimic the problem again. This causes me to believe that it is not bearing related as it seems that once that starts to go, it should continue to cause trouble.

I am guessing voltage regulator or something similar to what Jon has suggested. Yesterday there was a little oscillation or vibration yesterday, but once it got itself lined out it quickly smoothed right out under load. Could still be temperature related as the higher temps or longer run time caused something in the system to change - bad ground as Jon suggests, erratic voltage regulator, who knows? This even though water temps last weekend during this problems were not very high relative to what we normally run (160 vs 195-205).

One other thing that makes no sense - my oil pressure was lower than what I am accustomed to seeing - running abut 30 psi whereas in the past it has been 50+. Can't imagine that has anything to do with it but open to suggestion. Trying to figure out everything that is different or has changed since we had several hundred hrs of basically trouble free running.