Might just be the picture but that coil looks like its bulging a little. Might have over heated? You could start with a new coil sleeve to see if that helps.

They are normally pretty loose.

My experience is when they get sluggish it is because of garbage causing friction. Normally a coil will work or it won't at all.

I would take anything the moves apart as best you can and clean with rubbing alcohol to get off anything that is sticky. If you don't want to take it apart just do your best with a spray bottle of rubbing alcohol, swabs and rags.

You must take the coil apart and clean the inside of the sleeve where the plunger slides and clean the plunger, that can often be a mess.

These parts don't need any oil, but get them clean and dry.

Make sure that the solder joint to the coil looks good, reflow it if it looks marginal. Make sure the multi-strand wire that goes to power the coil does not have a bunch of strands broken. I have seen a few are that are getting ready to break off with only 2 or 3 thin strands of wire left.

Mg81 nailed it. My Pinbot's drop targets got like this sometimes, but since I gave them a really good cleaning and polishing and changed out the coil sleeve they've been very reliable. Its amazing what a small amount of percieved gunk will do to this mechanism.

Yep,it is surprising what kinds of problems will be cured simply by cleaning.

I would like to add that if you thoroughly clean the drop target mechanical parts and apply only a very, very small amount of quality molytone or teflon grease ONLY to metal on metal friction points - it will require less effort from the coil and last longer, taste great and be less filling. - and, do not lubricate the sleeves or plungers with anything.

Try a new sleeve on that coil.

I had to replace that bracket too and in doing so had to clean the sleeve.