How can I square up a wicker chair with a lean?

You could try reweaving or caning them. Over time the caning can become loose or even break. That could lead to a chair leaning since that would stretch out the caning. Also wicker that is outside should have some sort of sealer to protect the wicker.

https://www.hunker.com/12351366/how-to-repair-wicker-patio-furniture

Since you believe they are over “iron” as in steel, then I’d look at those joints.

if they are broken spot or tack welds, time to call in a favor from your welder friend.

if they are bolted or screwed joints, then you can examine how they failed and address that.

if the Skelton is broken, the skin cannot heal it.

Cathy

See if this is any help to you . Good luck

https://www.pinterest.com/pin/40110252901271984/

Try squaring it up using rope and a square. If it moves into place, the weaving has loosened. If the framework moves easily and the parts don't line up, it may be the framework. It's hard to know without actually handling it, but, that's my best guess. Good luck!

I'd try something a little simpler like putting a cap on the chair's legs on the side that's leaning over. It won't look as nice, but it'll be easier than re-caning or welding.

The easiest thing would be to add a felt stick on furniture pad under the wobbly leg.