Unfortunately I too am having trouble with a retro hydraulic roller lifter 340. Seems one is not holding pressure. Took all 16 out to clean and inspect, and found the suspect pair can be depressed very easily with a push rod.. while the rest seem extremely tight. I think I am going to roll the dice and order a pair of two and see what happens. I thought about placing the lifter in oil while sitting on a V-block and using z drill press with a push rod to pump it up and see if it holds pressure. I might even put a scale under it and see what pound force is...
