Before I even started using the ctx, I had heard of junk getting in the coil cover. I did searches in different ways to find out what to do about it. Many people had some good ideas, many were obviously not very good. But, for every good sounding idea, there were people who had a problem with that idea, or at least a possible problem. I decided to leave the coil cover alone. I don't hunt in sandy areas though. The most I get is a little grit and dust in the cover.
I did read about people completely sealing the cover with silicone, and others stating why this wasn't good. It was a while ago but I believe someone mentioned that no matter what, some part of the cover would start to come lose and junk would get inside. Then, with the rest of the cover being glued with silicone, you had a devil of a time getting the junk out.
I also wondered if silicone itself might cause a little falseing, but never did find an answer to that.