It could be that the finish on the arrows I was using when I first installed my 360 was sort of rough and wore down the plastic rest cap (I've since switched arrows).
I will say that after I contacted NAP on this issue, they were very good about sending me replacement brushes and the plastic rest cap (in record time I may add). The 360 is a good rest if your fletching is not ona very radical helical. If you're going to use the 360 I'd suggest getting some spare plastic rest caps, they're really easy to replace. Heck, this spring I may very well give my 360 another try, I did like the ease of adjustment.