Check the coil stop. I had the same problem on X-men and found the coil stop stud was loose. I replaced the coil stop and all was well.

Coil stop could be the culprit as was already mentioned, could also be the coil sleeve. Judging by the coil dust on it a flipper rebuild kit would not be a bad idea.

coil stops have been going bad on modern sterns. The stud becomes loose as stated above. I have replaced several on many sterns that have flipper sticking issues. Replace the coil sleeve while you are at it.

https://www.pinballlife.com/flipper-coil-stop-for-sternsega.html

Dive in and rebuild the flippers with new sleeves, coil stops and plungers. Best thing you can do to keep the machine playing like new along with regular cleaning and waxing. Easy and essential part of being in the hobby.

Also make sure that where red wire is sitting it isn't touching the coil bracket frame.
And you magnetised the flipper plunger and stop.

It looks like it is in your pic.

Screenshot_20190225-030241 (resized).png

This also happens when the plunger gets mushroomed at the tip...and then it drags and catches inside of the coil (sleeve) when trying to return to a resting position.

Take the coil stop off. Inspect the coil stop. Slide the coil off. Look at the coil sleeve. Look at the plunger. If stuff is beat up, flattened, or has sharp edges, replace them. For me, a flipper rebuild is: new coil sleeve, new plunger & link, new coil stop.

Also, as mentioned, the part of your coil where the red wire is attached has snapped off and is going to need to be replaced eventually. You can just get a new coil. Replacing it involves soldering those two wires. Even if you haven't done it before, it's not something you need to be afraid of.