I just wanted to add to this thread something that non-1266X users may not believe but is true in at least my case. This machine actually has a longer learning curve than most would think for a basic VLF turn on and go. It took me at least 10 years of heavy use to realize that I was still learning tricks and tones! I never thought that the 1266X would be something that would teach me so much about what's in the ground. The very fact that most machines are quiet until a non ferrous object causes a beep, make me wonder if I could ever go without all that chatter from the 1266X. It truly tells you everything that is going on in the ground by all the sounds it makes. It is the audio version of an I.D. machine except more accurate. As I advanced, the more I started dabbling in reverse discrimination which is now the most valuable tool in my relic hunting ventures.
There is something that I typed out for this thread 3 times before but deleted every time because I did not want to let this secret out to my competition but maybe this time I will click POST......
There is no other machine in this world that can compare to the 1266X at finding Canadian clad. When set on disc.5 and 7, a nickle all the way to a $2 coin, give a solid short iron like blip that does not disc. out. It is a killer on nickle based dimes and never misses them. A lot of popular brands do not even pick up Canadian clad and are designed more for American coinage. I clad hunt once in awhile just because it is like stealing candy from a baby with the 1266X! It is so easy to find $50 to $100 in change in one day with that machine. The signal is so different than copper, that I can leave all the new pennies behind and still pop out silver rings. I hunted with guys using Whites I.D. machines and a $2 coin reads like a penny. On the 1266 you know when you have a $2 and the signal is nowhere close to a penny signal. When it comes to Canadian clad, NO machine could out perform that old fisher and that I will take anyone up on that challenge any time!
Here's another thing. This machine is dynamite at Beach hunting. Especially in fresh water up to as far as you can go with it extended out. Push the sensitivity in to max set Disc.1 at about 2 and Disc.2 at just under 5 and you will never miss anything! Coins sound huge and loud and I find tiny little diamond studs with ease. You will never miss a fine gold chain. In wet set, I have dug rings and coins at 2 feet down and that is the honest truth. I have many witnesses for the previous statement!
Some beaches I've searched have been hammered hard by many others but I never feel disappointed because I find all the deep stuff and always get tiny gold and silver that other machines wouldn't pick up. I have written Fisher a letter asking them to make a waterproof version of the 1266X because it does so well at fresh water beaches. Two days on a West coast salt water beach after a storm, I dug up $320 in change! A record that is tough to beat. My best 6 hour clad hunt was $143.65 and a few rings. I'm telling you this machine is versatile and tough to beat in many different types of hunting.
In hunted out parks, the 1266X gives many iffy signals that have been goodies time and time again.It has showed me that it can see through trash well before all the machines came out using that advertising slogan.
I most certainly could go on about this machine some more.
I may delete this post because I don't want to go against another 1266X out in the field! Any other machine would be no problem but not the old Fisher! Especially if the user has many years experience.
After using Whites for my first 10 years, I remember the first day using my new 1266X. I was so overwhelmed by all the signals everywhere! I was used to a quiet machine beeping every so often. I actually thought something was wrong with my new machine because it was so talkative.
Thanks to the 1266X for making me a confident hunter.
THE BEST MACHINE EVER MADE!!!!!
Dave.
. Deepest coin target were two flying eagle pennys , stacked on each other, at 12-14 inches . Today , the old machine still works well , plus using it for 22 years also helps. 
CMD
for this post. You've already answered one of my big questions, and gave me lot's of info on how to use my old friend even better.
And welcome to this thread. It's never too late to get back into this fine hobby of ours. And your enjoyment level will be much higher now anyhow if you use the machine you used back then. The 1265 and '66 are still in-line with the new machines. I think that there is some information that an "old Fisher" user can get from their machine that the user of any other brand/model of machine cannot. Anyhow, enough said. There's already mountains of info up above. 
You hit the nail on the head. I have also used mine for beach hunting--and for some reason this machine will go through sand to an incredible depth. Yes, the learning curve for the 1266 is IMO the steepest for any turn-on-and-go VLF machine. It's quite incredible. It likewise took me about a decade to really master the machine--especially being able to tell what I was going to dig, how deep it was, and how big.
