Forget who did it, but someone worked on silencing their M with grease and found that after a couple months of usage it shook the grease out of the spring on high-activity keys. I've seen pictures of the spring in a Soft Touch and it really does look like it's just grease, but I have a suspicion it's a high-silicone content grease and it's 'seized' like an extra soft silicone caulk.