Between the coil abd cover...

Boy I wish I took pics of the amount of dirt, sand, and tiny organic material (pine needles ect) that I found when I took off coil cover. Today I had to correct the washers on the NEL coil on the TR. It was too loose so the coil moved sometimes on its own. I decided to remove the coil cover when I heard a little rattle inside. Turns out there was a ridic amount of caked on debris. I didn't think stuff would get between there but apparently it does. So this serves as a heads up to check and clean yours every once in a while. I have two machines with coil covers, but no hours on one machine so it's not gonna have any yet.

I've heard that excessive debris, especially if it's mineralized soil (rust, black sand, etc) it can really detract from the machine's performance, cause a lot of falsing and so on.

I am sure there would be some mineralization everywhere so you would be bound to get a few grains in there every so often. So I was thinking it could possibly affect the readings just a tad, after it builds up over time. It's like carrying an extra 1mm worth of ground with you every where you swing.

I take mine off all the time and clean them. Some guys use silicone around the edge of the coil cover to keep the dirt out. I never liked that solution since it would be a pain and messy if you ever needed to take the cover off.

I clean mine about every 8 hours of detecting and more often if I was in sand or a really dirty area, muddy, no grass ext. I thought is it doesn't take long to do and if it improves performance even slightly it is worth doing.

I have sealed both my detectors coil covers with silicone. I have no worries about removing them for cleaning, and when the covers are in need of replacement, the silicone will not be that hard to remove, as it doesn't take much silicone to make the seal.