What should I use and where can I get the adhesive to attach a DF puck? I used what came with it last year but I stuck it on top of what was already there and it didn't read right. I've ground down to the glass now but I heard there is a special epoxy you're supposed to use. Any help?

You can use a 2 part epoxy, when I was rigging boats at Cabellas we used fiberglass putty (that comes in a can at an auto parts store). Both work excellent and the putty is actually easier as it isn't as runny. Just make sure their are no air bubbles between the puck and the hull as it will throw the finder off.

Any epoxy will work. Having no air bubbles is the key. I even used some permatex silicone before and it lasted for a year and worked fine.