Most of my stock lifters at 221k miles had to be pulled out with vice grips , apparently they had some crud built up on them???
Lifters often have varnish built-up where they don't rub against the lifter bores. Pushing them down farther, or pulling them up higher than their normal travel can be difficult.
I cut the varnish with aerosol carb cleaner. Work 'em up and down while keeping them wet with the solvent works wonders.
Flat-tappet lifters can get the bottoms pounded-out by worn cam lobes. The metal gets peened-over at the bottom edge. THOSE lifters will score the lifter bore on the way out, making for excess oil leakage, low oil pressure, high windage--all sorts of evil. The lifter(s) need to go up just high enough to get the cam out, but no higher. Then push 'em down to remove so the lifter bores have minimal damage.
Either way, "forcing" lifters out of the bores is bad juju.