Reddit reviews Sherline Grease 7550 3 oz. Tube of Super Lube (PTFE)

Your paperclip trick shouldn't cause a problem. That is the standard idea for making an EM free play. The paperclip is a little unconventional, I might have used a short wire with alligator clips, but hey, as long as the clip isn't touching anything else and is allowing free play, then it should be fine.

Stepper units are a big pain when you don't really fully understand them. They need to be able to step and move freely. I find that it's not usually a coil problem, although cleaning out the coil/coil sleeve is definitely a good thing to do. More often than not, it's either a build up in the center bushing between the contact plate (the football) and the stepping gear (on the coil side) This bushing goes through the center of the stepper plate (the round one) and there is an "axle" between the contact plate and the gear. To clean this means you have to remove the contact plate. I highly recommend taking your time. You'll need to know how the stepper works... not electrically, just mechanically. Know that when one coil fires it steps the unit in one direction and when the other fires I believe it resets it (since this is a replay game and not an add-a-ball) Once you know how the stepper is intended to behave, then it's just a matter of methodically taking it apart and cleaning it. The hardest part is the spring. When you disconnect it, do it carefully and keep track of the number of times you go around the post to unwind it. When you put it back together, you'll want to rewind it the correct number of times. Too many and it won't step. Too few and it won't reset.

If you do pull it apart, clean that center bushing with the degreaser, and you can lightly lubricate it, but you need to use a good lube. Oddly enough, the best I've found is at Harbor Freight called Super Lube just a little bit is all you'll need. make sure it's the PTFE grease. If that's not an option for you, you can also try your local hardware or even bike stores for something called Tri-Flow. It comes in a small bottle with a needle tube applicator. Again, you only need a tiny bit.

The reason you don't want a lubricant like WD-40 is that it's flammable. Not a good idea with old cotton wiring and sparks. Also, lubes will have a tendency to build up dust and grime from the coils and turn to glue. That's why the PTFE is important, it's better at not collecting grime.

Most likely, if you pull the mech apart, clean and reassemble it correctly, it should work much better. If not, we can look at where you may be getting circuit resistance, but I would aim for that last as it's more difficult to figure out and also less likely to be the end all answer. If doing both things is going to give you 100% improvement, cleaning the mech is probably 80% of that.