When old damp or contaminated can react to microwaves by arcing. MODELS THAT THIS PART FITS NN-C877C, NN-K354B, NN-C827MB, NN-A883WB, NN-A880WB, NN-A873SB, NN-A872SB, NN-A850WB, NN-A813AB, NN-A811AB, NN-CT857WB, NN-CT867MB, NN-CT870WB, NN-CT890SB, NN-CT880MB, NN-C897WB, NN-C897CB, NN-C877WB, NN-C850CB, NN-CT878SB, NN-A850CB, NN-A823MB.
