I'm not going to recommend the oven technique which used to be a common fix for the 451, but you might try putting the capsule in a mic bag with some silica gel.
as these mics age, the electronic parts are going to break down, and they are not repair-friendly. At CB,I we had piles of 451s and 460s, and when something went wrong with them the techs whined a lot.
"I believe that entertainment can aspire to be art, and can become art, but if you set out to make art you're an idiot."
Show business: we're all here because we're not all there.
Resistance is not futile. It is voltage divided by current.