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I welded those feet that I made, onto the mill's movable base. While one stud became hard to turn, none became stuck. It was the first one that I welded. After some thinking, I realized that the decision to weld along the whole length of the bar, was wrong. I welded the rest, with four 1" long welds, along where the nuts are attached (most rigid areas). Remaining ones were not stuck at all.
Then I used a 12" Starrett precision level to level the mill. The level turned out to be very sensitive. After about 45 minutes, if not more, I finally got the mill leveled. It was a "step forward, two steps back" kind of procedure. But finally it worked.
At the end of leveling, I realized that the mill was only standing on three legs, with the fourth not touching the ground. Very embarrassing. I then slid a piece of paper inderneath that leg, and gently lowered that leg to the point where the paper just became firmly stuck underneath it.
I verified that the mill remained true.
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