[Amps] Air variable pitting - repairable?

[Jeff Maass]

We have a TenTec Titan III at PJ2T which is currently unusable because of serious arcing
on 20 meters. It is so bad that the amp will only run 300 watts.

The problem is clearly in the loading capacitor, an air variable. There is an area on one
of the rotor plates that is burned and broiled so badly that it has fattened up the rotor
and it is nearly coming into contact with the stator at the spot where 20 tunes up best.

Can this be fixed by sanding it down (and perhaps coating the plates with something) or is
this always going to be a "weak spot" on the capacitor that will start to arc again?

73,  Jeff  K8ND