totally agred with you Tin falcon
when I bought my mini-mill i knew very well that these machines need a lot of work to get it working right, that mean a lots of mods
i bought my mini-mill new from a store (mine is not made by sieg, is slightly diferent, but is the same thing after all) and i noticed immediately all the problems that had:
1) incredible backslach in the gear transmition, the thing was so tight that almost suck all the motor power (and ofcourse..i broke a teeth in the inner gear and made all the machine useless)
solution: belt drive (because my mini mill is slightly diferent, all comertial belt drive kits won´t fit in my machine) i done mine using a lathe and a drill press
2) X and Y gibs: the gibs work well, but with a closer look i notice that when tightening the set screws, the faces of the gib came out of parallel with the faces of the dovetail
solution: i made a new gib for the Y axis of brass, but that one shows the same problem, but still work fine, some day i will fix that problem for real.
3) Z feed and backslash: that had been said before, that knob is useless, and had a lots of backslach
solution: almost mine, a cheap dial indicator to measure the down feed (in steps of 12mm), and for the backslash, some day i will put a bigger hand wheel and some bearings.
4) column flex and disaligment: that is what im working on now, for the flex i will made a back plate, and for tram te column true to the table i will use metal shims, then more metal shims for tram the head true to the column
in time more problems and solutions will come, is a "blank machine" that has to be refined by the user, i have lots of fun doing this, and gain experience, because im a beginer.
i bought the mini-mill because I could not buy a bigger machine, too expensibe, I could hardly achieve the mini mill
well, hope that help you
Saludos!