I'd suggest evaluating the machine before stripping it. By moving the slides and other functions normally and abnormally (e.g. by leaning on the table & head etc), you may be able to feel problems, and a DTI will reveal fine misalignments and unwanted movement.

Once you've confirmed the problem can't be corrected by an adjustment, then it's time to take things apart and have a look. My experience is very limited, but – for example – rather than elaborately measuring a dovetail to confirm it's dimensionally correct, I'd look for wear with a straight-edge. As wear is unlikely to be even, it can often be spotted by reference end-to-end . As David George said 'The most wear on the slides were usually X axis worn in the middle so tight on the ends and loose in the middle'. This sort of error can be confirmed by shining a torch on the back of a straight-edge. Then the size of the error can be measured if need be.

As an self-trained beginner I found taking accurate measurements to be much more difficult than I expected. Also, when measuring a machine-tool, it's easy to be misled as to what the actual cause of a problem is. It it ain't bust don't fix it.

My experience of the forum is that's excels when you ask specific questions and can provide photos. Chaps like David know their stuff and are pure gold. Don't be afraid to ask.

Dave