Melted my key the other day, key box got really hot, kind of charred inside. Can substitute a fuse for a key, not sure what capacity, reluctant to do this until I know why it got so hot. Switch seems ok, evidence of arcing visible on contacts, seems reasonable. The leads to key box indicate exposure to heat, insulation appears to have thinned. Any advice? Anyone know of a circuit diagram? Any help appreciated. Thanks!