If the lifter is mushroomed at the bottom enough to make it difficult to remove, you can count on having a badly worn camshaft as well. Replacing a lifter will be a short term band-aid fix.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!