When working around many metal parts sometimes a magnet pick-up tool will not work.
Consider a Shop vac.
Tape a skinnier hose to the end to reach area.
Place a piece of panty hose at motor end of hose as a catch.
No shop vacuum...as long as no fluids are involved any hose type vacuum should work.

 

Mine was under the rocker on the left side intake valve.

 

I dropped a nut into the hole that has that little hose in it once.. never again. Not even sure if it would damage something.