You have to do short fast wiggles directly over really deep coins to get them to climb to 180. You have to keep doing this constantly until the ID climbs and reaches it. Also, you may have your sensitivity too high. If it's set too high the ID will become unstable and hard to lock onto one target number.
Think I'm finally home after a lot of years searching for my particular needs. Custom 1.5 lb lighter 
Sovereign GT (easy to do by just "building" lighter shaft) & SEF 12x10 as everyday coil. 8" Tornado (actually 7.25") as super heavy trash coil (Very deep & separates better than typical 8/9" true size coils). 13" Ultimate for large fields/beaches on certain days I want to grid faster than even the 12x10's nice improvement over stock for that. Stock 10" Tornado stays on water rig (stock shaft). 
ProPointer. Owned 15x12 & SunRay S-5 (5.5") at one time. Loaned a prior 13" Ultimate & SunRay S-12 (12.5").
Some Oldest Silver- 1835 Bust Dime, 1842 "O" Seated Dime, 1855 Seated Quarter, 1858 3 Cent Piece, 1891 Seated Dime, & another Seated Quarter too damaged to read date. Highest Value- 3 Cent Piece, Seated Quarter, & now 1921 F-12 Standing Liberty. Oldest Coin? Got to give large cents a good look & see. 2013 so far- 1 Seated Quarter, 1 Barber Quarter, 1 Standing Liberty, 2 Washingtons, 1 Barber Dime, 9 Mercs, 3 Rosies. 1 War Nickel. 19 silvers in total, & 1 1872 key date Indian, 2 Bufallos, 1 man's 14K gold medium sized ring & 1 gold chain, with possibility of few 8"+ deep mystery coins being Indians after cleaning.
What matters in life is the journey and not the desitination. How you handle that journey determines if you were a success, not so much what you achieved if and when you finally get there, especially if you made it by stepping on people along the way...
In loving memory of my long haired (wooly) husky Sky. She taught me just how beautiful and pure a soul can be, human or not...
