Bad lifters?

I have a 2.0 that has been sitting for a couple of months supposedly in need of valve seals, after pulling the cam's I noticed that the hydrolic lifters that were under load were soft, and the ones that were not are still stiff.
Does it ruin these lifters to sit under a load for an extended time or will they stiffen back up once they are filled with oil again?
The hanes book say's to store these lifters upside down in oil which is what I have done today, but is this alone enough to re'fill the bad lifter's with oil or is there some procedure to getting the oil back in them?
Any info on this would be appreciated.