Bummer, I gave you all the info on pulling end plugs, but forgot to warn you about those " hold a rag over me or I will take flight retainer clips"
Once they get past center, or 1/2 way out, they want to go away...Hope you have a clean shop & a vague idea where it went..Get your broom, a strong light , & a magnet bar if you have one...go trolling.........Good luck......
Slamming valve bodies is a method used to free up sticking valves....You must have a FLAT SURFACE a bit larger than the valve body that you are working on...Flat like a granite stone or a machinest's table......I have a 24" x 24" x 1" table on wheels that I used to use...You do not need anything that size, I used mine for other general machine work...
The WORD here is FLAT..........not even the top of your work bench, unless it is really flat,,,
Don't pick up the valve body & try to slam it as it is likely that you will not hit the table squarely.A warped casting will hang a lot of valves.
After washing it really clean & plucking all the valves, you can sometimes free up a stubborn valve using this method:
Stand the body on edge on your flat surface, hold it with one hand & lightly flop it down on the table, so that it hit's the table squarely.
This will embed any miniscule particles into the housing, on that side of the casting..do this a couple of times until you are familiar with what you are trying to achive........Then turn the body over & making sure that all valves are seated in their bores, use a small good quality screw driver and working down in the worm tracks, give each valve a tap to the left & to the right as much of an angle as you can, this will embed the same matter into the housing on the other side..MAKE SURE THAT THE VALVES ARE SEATED & only tap on the area BETWEEN the lands of the valve.
If you tap on the valve land you will ruin it..ONLY BETWEEN the LAND's...use a 3/4 inch wrench for your "tapper"....hope that makes sense....
Your choice of manual's is spot on........ATSG & ATRA.......manuals are the best you can buy..........best wishes, Donnie