I don't alway buy OEM, but I fersure always buy "new"....Just personal experience that goes back 30-35 years...that was when most shops rebuilt them using kits and drill driven hones....those they rebuilt never lasted very long.

So it was cool when parts stores started offering new MC and wheel cylinders at a decent price. Sure beat gettng them from the dealer or installing a kit....And they seemed to last a long time compared to rebuilt.

I ain't gonna say it's fersure the MC....But if I was you I would just go ahead and get it over with. I would jack her up and do a full brake job including hoses and fluid.

Use new loaded calipers, new wheel cylinders, rear shoes, perhaps new rear springs and hardware, new hard lines if signs of rust.....the whole works.