As andypen says, it shows tracking marks, so either physical damage to the cap or moisture has got in, not uncommon.
The arm goes nowhere near that far out, the presence of any apparent burn marks on the posts is ok, and does not affect performance.
Doing little trips or just starting up every now and again will cause condensation to form on the inside of the cap, I stopped this happening on mine by drilling the holes out a bit bigger underneath, there are four holes on the underside for "breathing", so I just drilled them out whilst my dizzy was apart.
tabetha