Another possibility: did the capsule get wet? Sometimes putting it in a container with a dessicant packet for a few days will resolve that. Or place it in the oven at 100deg for an hour or so.
Try unscrewing the mic body retainer (not just the mount retaining ring), then screwing it back in. Sometimes the anodized area in the threads doesn't make good electrical contact, though this is usually only a problem with new mics.