I'd also try one of the four pronged spring loaded grabbers. They also are usually 99c and since they are not magnetic and also flexible, they are very useful in tight spaces. Open it up slightly, push it down the hole until it encounters something and let it close. With a nut, there's a good chance it will go thru the hole and grab it.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13