Annoying click when touching a couple of keys on 42S

[Dave Britten]

I've got a 42S that I use daily, and it's developed a habit of making an annoying clicking sound when a couple of the keys are touched even lightly. If I firmly press the key and rock it back and forth a bit, this often silences it temporarily, but the sound usually comes back within the day. This is not like the issue with Indonesian 32SIIs where there's a loud popping sound when releasing certain keys, it happens when the key is lightly touched, and not even pressed. Is there a known fix for this? Should I inject a small drop of something around the key to clean it out? (Distilled water, plastic-safe oil, etc.)