That flipper coil likely overheated at some point. With the dual flippers like that if it were a fliptronics issue I’d think it would be both flippers sticking on the side in question. Something else to keep in mind, when you move the flipper with your hand, you are applying much less force and applying it in a different method (pushing the plunger via the bat vs the plunger pulling in) so the forces will be different. You can try wiping the flipper opto with alcohol and a cotton swab and see if that helps but it’s a red flag that the new sleeve wouldn’t fit in. That old sleeve was likely Blackened from use and has grime in it that even if it doesn’t feel like much, can cause sticking. Also check to make sure the flippers are gapped properly and are not dragging on the bushing or even the playfield in extreme cases.

It’s probably not the springs. As long as you got a fliptronics rebuild kit you have the right ones. I’m betting you replace that coil and you’ll be golden. Make sure you wire it up correctly though or you’ll have a new set of problems.