The downside of buying after market coils is when you have an issue such as just what has been posted. When a coil malfunctions, it could be the coil and or the electronics. If you purchased a Garrett coil, they could replace it and/or be able to get the two in balance working. They have the ability to service both. If it's an after market coil malfunction, you hopefully get a working replacement, If the replacement coils don't work, you will never really know if it was a faulty coil or faulty electronics. "Nel" coils cannot service the metal detector, only the coil. Buying Garrett allows you to have "both" serviced.
I too had a faulty after market coil for the GTI Series many years back. I never did get a replacement, as the direct supplier had moved with no new forwarding address. Now don't get me wrong.......there have been some decent after market coils put out in the last couple of years. PLEASE find out what type of warranty there is for your after market coils. Is it replacement warranty or can you get your $$$ back.If your metal detector is tuned to the factory coil and the after market won't give decent results, chanced are that the replacement coil won't either.
Good luck with your dilemma. Hope you get it resolved.
