Sounds like the coil could be toast (weak, tight when replacing the sleeve). Any signs of it overheating, like singed wrapper, etc?

Also, the mechanism should move with basically zero resistance. If the coil overheated, it constricts the sleeve which in turn runs on the mech.

You might want to check the resistance of the coil using this chart: https://www.flippers.com/coil-resistance.html If it doesn’t test close to the listed measure, coil replacement might be in order.

Wait a tick... I'm not sure you have the right plunger there. Mine looks more like this:
https://www.marcospecialties.com/pinball-parts/A-6306-2

I'm at work, so can't confirm it looks exactly like this, but I do know that it's got that smaller diameter part with a rubber bit on the end. Tried a little too late to grab a ball headed down the left outlane post-rubber swap and managed to get a blood blister of that exact shape and size on my thumb

IMG_5715 (resized).JPG