When changing out the old stock valve springs it seem that the #1 intake lifter did NOT compress any if I pushed down on the push rod (The car set for several years), This weekend was my first chance to drive the car any and sure enough I’ve got a slight valve train tap on that side. I’m thinking the plunger is stuck, lifter not pumping up or something like that. I would like to gets some thoughts on changing just one lifter or the thoughts on something to add to the oil that may help the lifter out if it is actually stuck?