Grid Heater bolt failure. Grid heater bolt is secured by a nut below intake area. The nut on bolt melts and causes pieces and shards into cylinder #6 if not fixed immediately. This is a terrible design and expensive fix. I am 3rd person to have this problem recently amongst my friends. Metal in side motors should not be melting and or rotting into cylinders. Please see attached pictures showing melted bolt and shards in the intake area. If this is a part that needs maintenance it should be listed in the scheduled maintenance somewhere