Mine wasn't really intermittent, it just sort of died. The problem though was that one of the screws that holds the brush assembly in actually stripped out, and it happened to be the screw that made the brush pack contact the wire. If it was loose, or just rattleing around in there I suppose it could be intermittent though. Like they said though, I'd at least pull it apart and check the brushes, cheapest option to start with.

86 4runner, pro comp AAL, Kayline Soft top, 31's but all stock