Had a Mole Richardson fan come back from a tour today. Said something about the dimmer sparking and the dimmer area getting really hot when on a low setting for a while. This fan has a semi-exposed variac dimmer that is easy to see within the housing. Somewhere at about 90% there seems as if some kind of nick in the dimmer wiring. When the brush hits this area it sparks but continues working. No sparking or anything unusual observed about the lower dimmer setting. What’s the possible theorized problem that caused the extra heat while on a low dimmer setting yet not on other settings persay in relation to the sparking at the higher dimmer setting? Splain please how the sparking at a higher dimmer setting could overheat while the dimmer is on a lower setting..