had a friend bring me his cl350 to work on, the number 2 exhaust rocker arm shaft was stuck and wouldnt turn to adjust the rocker, I pulled the top end apart replaced the shaft put it all back together, now none of the rockers will adjust tight enough to be within spec for the valve clearances. I can get them relatively close but when i tighten the lock nut it loosens up (even though i got a good lock on the rocker arm shaft with a flathead screwdriver and make shure the shaft dosnt rotate.) it also feels like the rocker arms go from being free and moving up and down well to really tight when I lock down the lock nut. I looked at the rocker arm feet that ride on the cam lobes and they dont seem chewed up or worn down, niether does the cam itself. anybody run into this? warped head? my mistake? something else? Ive rebuilt a couple of these engines before and have a fairly decent working knowledge of putting them together but i cant seem to diagnose this