Well, I threw everything I knew how to do at it last night. I timed it again, and from the back this time. I don't like how the Slants look for timing, they always look advanced. 5 out of 6 of them came into the house noticeably advanced, meaning that there's about 3/16" - 1/4" of the hook past the eye of the needle when the lower timing line is in place (one was out of time and the gears loose when it arrived), but the other 4 of them sewed correctly. I was trying to set it the same as the others, and it wasn't working. I figured last night, unless it hit the hook, what did I have to lose by timing it the way it says to in the manual?
Between that, centering the needle in the hole (it still swings a tiny bit more to the left than the right), raising the feed dogs (found the bobbin case from another machine was getting hit by the dogs, so I set the dogs correctly), adjusting and readjusting the bobbin case retaining bracket (get it wrong and the thread makes a "snapping" noise as it goes past, and makes the tension go haywire), lowering and turning the needlebar a tiny smidge, re-setting upper and lower tensions,...
It's no longer skipping stitches. 
I just didn't want to disassemble, reassemble, test, disassemble, reassemble, test, disassemble, reassemble, test - so I did a multitude of things before testing, so I can't tell what exactly fixed it, but I suspect that it was a combination of a bunch of things.
I'd still like to know though, why all of the slants are advanced despite what the adjuster's manual (AM) says, yet sew just fine 5 out of 6 times... does anyone else have a slant that's actually timed the way the AM says (ie the hook point is behind the needle at the lower timing line on the upstroke of the needle?) Part of me wants to re-time the others, but the rest of me just wants to put all of the slants in the corner and forget about them and go sew on one of my less belligerent machines.
Hey Miriam, think of it as a character building machine.
Like my 431s, there's a lot of character being built. I'm probably turning into a caricature of myself thanks to these machines.
You say the machine "is" out of time, not "was"... so with the dropping of the needlebar, still out of time, it's not skipping stitches?