usually when I have plungers stick like this, its because my coil is slightly in at an angle. Loosen the coil stop and loosen the plate that the coil sleeve sits through. Let them sit a little loose and move the plunger in and out. try shifting the coils angles until it feel perfectly free. Then tighten down the coil stop and then the holding bracket. Then test by hand. But do this with the playfield angled out, not flipped up. I've had some that were free , with the playfield flipped up, but tight when in it's flat position.