Normal procedure for arcing is to
repplace
the plate or the entire variable
capacitor.
K4DLI and I both had LK-500NTC no tune amps that
had setting for each band. The capacitors were OK but tended to arc.
The space available for replacement was not very big and the ideal was to
replace the capacitors with a small vacuum variable with twice the power
handling capacity. Several years ago Allen Bond (MGS4U) had some almost
pencil thin vacuum variables which I have seen at other sources.
I can't speak to the tape described in the October
2012 QST article but I would sure hate to be in the middle of a contest
when
an arc cut through the tape.
Just my opinion.
Dave K4JRB