Jim,
I'm happy the machine is behaving better after a FACTORY RESET. That is only --so common-- that while fooling around in the settings, or trying out a new setting and forgetting to set it back to where you like it...one runs amuck and gets something set really wrong. This happens on a daily basis with ALL makes and models. Sometimes a FACTORY RESET just seems to clear out and "re-fresh" the machine, just as we do "re-boots" on our desktop, laptop, and mobil device (phone) computers fairly often. Now since high end, high performance machines like the Nokta Anfibio Multi are run by powerful computers, would not the same tactics of re-booting apply from time to time???
Might I suggest another approach from a different angle Jim? Instead of using notching, how about trying using one of the NICEST FEATURES EXCLUSIVE TO THE ANFIBIO MULT? What I am referring to is the --TONE VOLUME--... If you read your manual on this, it is very easy to do, even the first time! What you will have is 5 different "groupings" of VDI numbers that you can adjust the VOLUME down from the default number #5. (The range is 1-5...five being loudest) Now without weakening the machine's depth with discrimination or notching (since you infer that affects the depth as well) try using the TONE VOLUME for a test. You can easily look at the VDI numbers (first and last) for each grouping, the one showing is the one grouping that will be adjusted, and then decide which ones you wish to adjust the VOLUME --DOWN-- ON. Simply when you see the number 5, reduce it down just a number or two (remembering each number with having only 1-5 will be a large 20%...so go easy at first as you really want a chance to hear the results. Or should I say "not hear" the results! (;
I set the first grouping down to #1 (of 1 to 5) to effectively cut the sound down to --next to nothing--...TO ACT LIKE DISCRIMINATION --WITHOUT USING ANY DISCRIMINATION--!!! We all know regardless of the brand or model, that discrimination cuts the machines ability to run clean and strong will full power and depth. Simply put...the computer must now spend processing power and time, working on disregarding certain targets, instead of using its full power LOOKING FOR TARGETS!
A --very sweet- option once you get comfortable with using --tone volume--. You may Jim...want to just start with doing that as a first test step. Then you hear the iron and scrap as only a slight background sound which IMHO...is always far better than total silence. I want to know what is down there, to know the area, to know what I am up against, to know I need to scan slower if in heavy iron, to know some of the target numbers will be off a digit or two, to even (if you know you are in a good producing historic area) consider a quick coil swap from the stock 11" down to the 7" CONCENTRIC as mentioned by SVEN...or my favorite "IRON EATER"...THE 9" CONCENTRIC from Nokta/Macro. The depth will still be far more than you want to dig (26"+ on a confirmed iron target I dug with the 9" concentric). My 9" Concentric "Iron Eater" stays on 90% of the time, except for the open beach and open flat field use...then I put on the 'Big Dog" the Nokta/Macro 15" Elliptical. Bring a BIG shovel if you have the 15" on! (;
IMHO...I see no reason to go out an buy any aftermarket coils (if even ever offered) as the stock Nokta/Macro lineup is HUGE and 2nd to none. Build quality and performance tuning is spot on. May sound funny, but when the big 15" elliptical arrived, I opened the box and picked out the coil and studied what gorgeous shape and lines it truly had. Someone who had to be artistically inclined designed this coil. It is a masterpiece!
On the weight issue Jim...might I also suggest a smaller coil, then to counter-balance an already nicely balanced machine...install the EXTERNAL BATTERY PACK with the RnB Li-Ion rechargeable pack available from your dealer. These were made popular with the Garrett AT Series, and fit and work PERFECTLY in the Nokta Anfibio Multi machine. Then your battery life will be longer than you and I used to last for when we were detecting 30 years ago!!!

Good Luck and God Bless.
PS: Please let us know Jim if you give this TONE VOLUME a try. I think you might just be pleasantly surprised with the results.