I have melted the ones on my performer like three times. Weber will send you new ones, but I melted those too. After the third time I just left them all deformed. At about 600 they start to go, at 800 they looked like melted candle wax and drizzled a string of plastic onto my deck. Obviously they aren't designed for heat that high, but it doesn't say that anywhere. As for that tiny washer it prob wouldn't have made any difference at 700-800 degrees. If you feel you need a roller go get an aluminum tube, cut it and slide it over the wire.
Brian