There were a few FP generators that had this problem [ I had one], Panda was very accommodating in arraigning a replacement within the warranty period for a new 4200. At this point he really needs to work with Panda and I would go to the head of Service/warranty. But my bet is this unit is 5+ yrs old cause the one I had that failed was installed in 2003/4 ish. I don't have who I worked with handy but it was a few yrs ago in 2006.
contact info is here
Fischer Panda Generators: Marine Generators, Diesel Generators, Commercial Generators and Military Generators Manufacturer
Having the serial # is key for any discussion.