Lifter Not Pumping Up

A while ago, I corrected the preload on one of my lifters to remove a slapping sound coming from cylinder 6. Having had great success, I decided it might be good to correct the preload on all of the cylinders, since the valvetrain seemed a little noisy overall... Not my best idea.

Unfortunately, I followed the first method I found (spin pushrod, tighten until it resists, add another half-turn) which resulted in severe over-preloading. The engine wouldn't idle correctly, and I wasn't liking the noises it was making; I shut it off quickly, less than 3 minutes.

I backed everything off today, and tried another method, (tug pushrod up-and-down, tighten until it stops, add additional half-turn). This time, with a lot more patience.

Now, cylinder's 3's intake lifter doesn't seem to pump-up. I can easily compress it by hand, even after running for a couple of minutes. The slapping is awful, and I've been worried about running it too long in this condition, so a couple of minutes is all it has ran.

Is it likely I blew the lifter with the over-tightening? Or could it simply be stuck due to the transition from valve-always-open compressed to proper preload? I read somewhere about running the engine until it warmed, then 'shocking' the lifter with quick bursts of high-revs to unstick it... sounds like a bad idea.

The lifters themselves are Lunati's, about 3 years old, with about 10k-15k miles on them. If anything, they've been slightly underloaded for most of their life, in an engine that has seen over 4k RPM maybe 10 times in its rebuilt lifetime, and never over 5k RPM.

Thank you.

EDIT: I'll also note that the car has been sitting for a couple of weeks, at an incline. When I first adjusted the lifters, I noticed that the forward four cylinders where all much squishier than the rear four cylinders.