After looking at the bolts more closely, it isn't nylon showing on the bolts. It is the metal threads of the nuts. The bolts themselves look fine and they are Grade 5 bolts. I will pick up some new washers and nuts this evening and replace the bunk. I don't have the bottom plate but am hopeful that BPS or Tracker will replace it for me. But for now the Heritage will be back and ready for the water tonight.