osewme, Thanks. Yes, I found that blog post too. He seems to be talking about pins you can access from the other end. The pin in the bed of the 403A can only be gotten to from the top. So, if I drill it out I'm drilling toward the aluminum of the body of the SM and might hit it. I'm not sure that's a good idea!
If I don't hear any other suggestions I might give it a go...very carefully.