My st70 has developed an intermittent hum.
I have traced it to the multi-cap. When I touch
or twist the cap slightly, the hum vanishes,
temporarily.
Could this be a ground problem, speculating
that the metal in the twist-locks are not making
contact with the chassis? There is a lot of play
between the cap and the chassis. Or, could
the cap be on the verge of 'leaving this world'?