Replace all five of them now, that damage is either from heat or corrosion I install my own, I install the rear one first and then test fit the cam into it, if it fits fine and spins fine I do the next one and so on If it or another one doesn't fit and spin easily I fixed that one before installing the next one and so on Good luck, let us know your results
do you leave the old ones in and remove and inst. them one at a time?
