TotallyDiggingIt: The only adjustment I know of are the 2 shifter cables (the "shift linkage"). The self-adjustment procedure is in the Bentley guide, and I don't know how useful it is if you just want to make a minor adjustment ... it seems more useful if the thing gets really out of whack. I have an example of a discussion thread about that,
In This LINK. What I do now is, occasionally I manually slide one of the cables (shift select or gate select) by a couple of little "teeth" (threads/grooves), one way or the other. I think I've got it almost just right at this point.
I don't know how to solve the 3rd-gear funny selection, but mine is doing a bit of that now. By the way, what transmission code is yours? Mine (2002) is an 02J type, code is EGR. (128k miles at present.)
I have another issue, where the reverse-gear selection makes a big clunk and tends to grind upon selecting reverse. After reading a couple of comments here and there (I think on forums.vwvortex.com), I have become accustomed to depressing the gear shift knob, near the left-most position (not up to R), then while keeping it pressed in, I nudge it over to the right, almost up to 3rd gear position, then nudge it back to left-most, then finally up to R. (All while keeping the clutch pedal depressed.) Now, I pretty much can avoid all of the thunk and grind when trying to select Reverse gear. (But, "WHY???")
I've seen one or two posts about how to drain and fill the gearbox oil, but there's almost nothing to it, you need to locate the two plugs (which should not be a problem) and then use a 17mm male hex key to remove both the drain plug and the fill plug. I picked up a 17mm fitting at my local auto parts store, and I use it with a socket wrench. The drain plug is kind of obscured by this pipe, I don't know which pipe it is, but I loosen a couple of clamps nearby and then the pipe slides out of the way somewhat. Here are a couple of forum threads, they're not perfect, but ...
only 4 pictures are viewable on the 2nd page of this one, and
this one seems to be for a different transmission type.
This FAQ thread on the Vortex doesn't show pictures of the procedure, but it has a lot of detailed information about changing that gear oil.
Regards, Larry.