Here are my experiences with Tesoro service:
1) Had a 5.75 coil I bought used with the 8' cable. I sent it in and they shortened the cable at no charge.
2) I bought a used Cortes in 2008 that was defective. It would sound off all the time, and when you passed a coin under the coil, it went silent. Total opposite of how it should work. I called Tesoro, and spoke with James, then president of the company. He walked me through a few things to try, then suggested I send it in for repairs. He told me that if a machine has no visible signs of abuse, they would fix it for free. He was very concerned that he had a machine out there that wasn't working right. I sent it in, they fixed it, and tuned it. It worked like a champ when I got it back.
3) I bought a used Tiger Shark in November, and it has a lot of issues. The sensitivity adjustment did nothing, and the GB was all funky. I could get about 3" max in an air test. I sent it in, and they fixed it for free. I had a nice hand written letter from Rusty included in it, including spare parts I may need. When I got it back, I noticed that the headphones only had sound in one ear. I e-mailed Rusty directly, and he was very apologetic for not catching that, and strongly suggested I send it back. He said he would watch for it and move it to the top of the queue. He e-mailed me the other night at 11 pm to tell me he put on new headphone, double checked the tuning, and would have it back in the mail the next day. He was very apologetic for the issues I was having. I should have it back in a few days, no charge.
In all cases I made it perfectly clear that these were used machines.
So don't even dare questioning Tesoro warranty to me. There is no MD company out there that would treat you like this. I currently have 3 Tesoros and will be a customer as long as I can swing a detector (I'm not that old, so hopefully that'll be a long time!) .
Dan
Dan