How does one successfully realign a bent mech cage?
It’s a bit hit and miss TBH.
1) You can do it by eye just bending/twisting the bottom jockey wheel part of the cage whichever way looks best, but it’s difficult to judge because of the floating wheels.
2) Unscrew the cage stop screw and roll the cage a full 360 degrees backward to release the spring pressure. Then you can fully dismantle it (the cage is 2 plates), get it on a bench/flat surface and bang it flat. This is hampered slightly by the fact some cages have relief profiles, hence are not a completely flat plate of metal (XTR are carbon so no dice).
3) Buy one or both cage plates separately from SJS, JE James or similar
Edit: I am talking Shimano here!