Conversion Chair Base Kit for Aeron Chair to Aeron Stool (Casters for Hard Floors)

We had very old first-generation Aeron chair that we could not use and needed a counter-height desk chair. We stumbled on this and our problem was solved at a reasonable price. We had a terrible time getting the cylinder out because the chair is so old, but emails to the seller were answered right away with great advice. Could not be happier.

There's no instructions and some of it looks like it's going to be held by friction and your weight which could be ok, but the pieces mostly fit an old aeron chair I have. Unfortunately the caster wheels don't hammer easily into the circular base. There metal "stem"/bolt is off center and too short from the rest of the wheel so it's been sitting around for months while i try different things, but it mostly wobbles off center when I try to hammer it into where it goes. I'll probably have to spend some more money to hire someone standing outside of home depot to figure it out. Or find someone with small fingers who doesn't mind getting their hand hammered against...