May not have anything to do with it but when I got my PRW 1.6 rockers I stripped them down and ran them through the ultrasonic tank. Then I still had to clear every oil port hole with a wire. I’d say 30% of them were packed with chips or crud. I cleaned the shafts out as well as I could without removing the plugs but I may go back and do that again because I haven’t installed them yet. If yours weren’t cleaned out before they were put in you could have restricted oil flow on some. Either way with any of these parts it’s important to pull them down and clean them out because manufacturers are taking every shortcut that they can to save a buck.
I also don’t like the color of those bushings and the deposit on the shaft it almost looks like there’s too much copper or wasn’t blended well so it could be an issue with the material