How do you fix wobble in a bicycle chain wheel?

First you need to determine if the wobble is from the chainwheel or from the bottom bracket. Then there are different procedures depending on if it's a sideways wobble or a bac/forth, up/down wobble. A sideways wobble can be adressed by bending the chainwheel back into plane using two wrenches/vise grips. One is used for bending, the other as a brace to stop the bend from going too far.

a back/forth wobble can be fixed by undoing the chain ring bolts a little, and then, with a piece of wood, knock the chainring back into position before doing the bolts back up again.