My son's 1962 401 is making noises on start up after being parked up in the garage. It started out as loud knocking and ticking from the top end. I thought it might be stuck valve but we took off the covers and rockers and all the valves are seating. So went ahead and took out the lifters. So the question is, looking at the lifter contact surface what do you think ? Also can they be serviced / freed up by taking apart and cleaning up and put back together. It's not that easy for us to duck down to NAPA and buy a new set. Shipping is expensive and will take at least 2 weeks. Hoping to get away with getting these to free up and replacing on a possible re-build in the future. Will there be any success ?