Instead of the quiet whirring sound of a fan when in float stage, the
charger has recently begun emitting a louder "whining" sound. The
fan's revolutions also seem to slow down when this happens. It
returns to normal if I insert a finger quickly and contact the fan.
But it often resumes "whining." At this moment, it's nice and quiet,
but the noise mode is occurring more frequently?

Is this damaging or dangerous? Does it need a new fuse? Thanx, Jack