So...after about 2 years of continuous enjoyment to and from work every day, both sockets on my 4Rs have begun to loosen up. I haven't come across any fix other than send them back to Westone. Granted, I didn't spend a ton of time looking, instead I've decided to try my own solution.
What I've done is simply make a very small shim out of a toothpick.
All you need to do is take a standard round tooth pick, and with a pair of needle nose (or small) pliers, gently crimp one side of the toothpick at its point so you flatten out about 1/8 of an inch or so.
I found that on mine pair, the side with dots seem to be the place to shim the gap. All you do is take the portion of the toothpick you have just flattened and gently shim the gap. Once it becomes snug, just snap it off and gently pack the portion that has filled the gap with the other point on the toothpick.
I've had this working for a couple of weeks and all is good, hopefully it works for you.