Generator began running rough then finally just died. While attempting to restart I heard an odd hissing sound. Immediately thought I had a valve too tight. Opened it up and the exhaust valve was no longer in it's retainer. After removing the rocker arm the problem was evident. The valve had worn it's way through the valve spring retainer. I did some digging and could only find one other instance of this happening so I'm assuming it's pretty isolated.
Top one is the replacement:
Best video I found on how to replace it:
Linear Mode
