Well, the "stuttering and jittering" mentioned last night became a huge problem. The stepper not only lost steps, it plain got stuck and didn't go where I told it to. Naughty, naughty! However, upon the suggestion of a great friend of mine, I hosed everything down with a good coat of WD-40. This XY table was, after all, an old CNC machine and was certainly exposed to dust and CNC debris. After everything was coated in WD-40, both axes worked absolutely wonderfully! It is such a relief knowing it all works! I hypothesize that the Y axis became difficult to move because it was exposed to the dust and debris, while the X axis stayed nice and pristine because it was under the CNC table, out of harm's way.
With that barrier overcome, it is time to find some more (really, life?). To oil everything with WD-40, I had to disassemble the sled that rode on the Y screw. When I put it back together, it contracted some backlash issues. Basically, when the motor reverses direction, the screw spins for a few tenths of a second before the sled actually begins to move in the new direction. I don't know if this will be an issue, but in the world of trading old problems for new ones, I would say this is a pretty good trade - at least the stuff works!
I also dug into my stash of DVD writers to extract the writing laser tonight. I tried once and didn't see what I thought was the right laser, so I wasn't as careful as I should have been and the laser diode got broken. Then, I was more careful on my second attempt with a new DVD drive and got the laser out. As it turns out, my laser is an open can diode rather than a closed can diode. That is why I didn't recognize it. Below are pictures of closed and open can diodes.
Conclusion for tonight: overcoming problems is not fun during the process, is rewarding in the end, and is a requisite part of any project. Did I mention it wasn't fun?