It had something to do with Minelab raising the price of the upper shaft for the E-Trac. At least that's the story Ralph gave. (Ralph at Sun Ray.) Ralph always bought extra upper shafts and mounted the X-1 target probe control switch to them. When a customer bought an X-1 target probe he always provided an extra upper shaft so if the target probe ever needed serviced, you could just switch the shafts out and keep using your E-Trac instead of sending your whole machine in.
When Minelab raised the price of the upper shafts to something like $100 it priced him out of the market. (According to him.) I think it also created some bad blood between him and Minelab, as he felt they did it on purpose to make things difficult for him.
I personally feel that he could have raised the price of his target probes by $100 and people still would have bought them. I sure do love mine.