Mine doesn't wobble in the least. But I also admit, mine was used off CL from ferrets who had gooked it so bad, I had to take a flat head screwdriver and sledgehammer to get it apart to destink/gook the cage. Then I just used a mallet to get it back together all the way. I got the pieces set in place so it held mostly still, but wobbly. Then DBF held cage and I whacked it together.
Some chips on the outside powdercoating, I think it's from the screwdriver being used as a wedge to break apart the gook or the sledgehammer. The girls, despite all attempts at cage destruction and evil doings, can't get to the chipped area and they haven't yet been able to pee on those areas, so it's a minor issue.
I think it was a bit "warped" on the side opposite of the shelves until I ordered more shelves, so they have two shelves per cage half. Keeps it nice and square. I also fully suspect we did the warping with the sledgehammer.
Mallets work fine to get the cage together. I suspect if I have to break it down again, since it's not ferret gooked, the mallet would work to get it apart. Sledgehammers are a bit excessive.