My garage floor has sunken enough to take the door out of square. Logically, I have big problems with the opening and close (the swing-type of door with the big vertical springs).

I believe the right thing to do is jack up the sunken corner (it's the back-left corner) to level, and re-pour the bad part of the floor. Then fix the door.

What kind of jack would I use for such a task?
Dan Scott
Allen Park, MI