My driver side seat won't recline anymore. Whenever I press the button, it seems like it engages but is stuck. I've taken off the cover and sprayed WD40 all over it and tried to use a flat head to help unjam it but still unsuccessful. The motor still works perfectly so I know for a fact that I don't have to replace the motor. Any suggestion on what else to do? Thanks

I would check again. It very well could be something jamming it up like a pen or change.

Inspect the linkage and slide bushing mechanisms under the seat.
May need lubed or cleared of obstructions.