I did this mod many years ago (probably circa 2003/2004) after reading about the “soft touch” version of the Model M produced by Lexmark. The main motivation was some grumbling from my co-workers (even though the guy right next to me also had a Model M). The grease suppresses the “ping” of the buckling spring without affecting the feel of the keyboard too much. It still feels tactile and still has a click. I did this to my 1994 Model M (which I bought brand-new back then).

After some experimentation, I found that placing a small amount of dielectric silicone grease into the springs, avoiding the sides of the barrel, works the best. Using a toothpick or paper clip, I dipped the end into the grease tube and twirled it inside of the spring. The goal is just to dampen the ringing of the spring, not to slug the movement of the spring in the barrel. I used a small acid brush to remove any grease at the top of the spring, which can prevent the spring from seating correctly back into the key. If some grease gets into the barrel, it can be removed with a Q-tip and rubbing alcohol.

Adding more grease gives the keys a softer, slower feel, which I didn’t like. Trying to fill the cavity of the key can render the key intermittent or even inoperable. Definitely avoid greasing any of the stabilizer pins/inserts on the wider keys and the space bar. Some grease on the wire space bar stabilizer is OK and eliminates any rattle that it may have.