Hughes "retro fit" lifter not pumping up!

All i know is that when i would pull my valve cover off the next day, valves that were on there lobes had collapsed. Ss in, the lift at the spring had been reduced. NOT that the valve train was loose, just that the spring pressure was reduced.
No clatter at start up...........which is why i made my statement above.
And these were Mother Mopar Hyd Lifters of 10 years ago.