I've been playing with removing layers of wire from the pop bumper coils in both Magic City and Slick Chick lately...and with great results. Both games are much more fun to play with the poppier bumpers. Slick Chick in particular was just brutal before the pop bumper improvements - not much movement in the upper playfield, almost impossible to hit that top center target, etc. After removing 2 1/2 to 3 layers of wire from the coils, there's much more action up there, the ball seems to spend more time in all areas of the playfield....it's just way more fun now and feels more balanced.

I went with removing wire from the coils because cleaning the metal slug/sleeve/moving parts of the pop bumper mechs didn't have much effect. So they weren't "weak" because of cumulative friction over the years.

Was the game designed with weak pops? I've heard Wayne Neyens say that of the games he designed, Slick Chick was his favorite game to play.... it's hard to believe that it was anyone's favorite game before making the pops stronger.

So I'm wondering - do coils weaken over the years? And if so, why? It's just a single piece of wire with a given resistance - that's not going to change, is it?

What I did before playing with the coil wrappings was: took mech apart, got rid of any mushrooming at the end of the slug, polished it with mother's/steel wool/microfiber until it was nice and shiny and smooth, replaced the sleeve, smoothed the top of the coil stop/cleaned it, cleaned and polished the steel bumper - again, mother's and steel wool (don't worry, I don't use steel wool over the machine - I take it outside for that), cleaned the yokes, cleaned the bottom of the spoon switch (and all other switches) with the dremel/alcohol, cleaned the bottom of the skirt that sits in the bottom of the spoon, cleaned the spring.

With that - not much change. Everything felt nice and smooth - nothing binding or tight....just not very powerful. So I went with unwrapping the coils and bingo - like night and day. I'd heard that Steve Young sells stronger pop bumper coils, but some folks said they were too strong, so I tried doing it manually. I'm very happy with the results.

Thanks @MarkG. I understand just enough about coils to realize that there is a point of diminishing returns - that removing loops (resistance) only works to a point, then at some point you have removed enough loops to weaken the magnetic field and are being counterproductive. Apparently, 2 1/2 layers of wire hasn't hit that point because the pops are significantly stronger, but not ridiculously so to a point that would be inconsistent with what I imagine the speed of the game should be - I don't want it to play like Metallica. I was trying to find a balance and I've been happy with the results - it feels like "customizing" the strength of the pops. I actually did it in stages as I was nervous about it - tried 1 1/2 layers, then 2, then 2 1/2 before it felt "right".

I agree that the cleanliness of the contacts and gapping of them is critical. I did take some time to make sure the EOS switches were opening late-ish - made sure to clean the contacts in the relays associated with each pop as well. I chose not to re-build the mechs because I thought the original parts were in very good shape and cosmetically, the blue plastic had this marbled look that I really liked, and wasn't reproduced in new plastics - so I chose to clean and polish what was there. Granted, there will be some friction that wasn't there originally, but what I was concerned with mostly was whether there was significant slop in the linkage to the slug or the yoke (there wasn't), getting rid of any corrosion on the metal parts, getting dirt off the plastic parts and out of joints - basically, anything that I thought would cause friction - and re-soldering the connections to make sure I had good electrical flow.

To do a meaningful comparison, I probably should have rebuilt one or two pops with new parts with the coils in their original state, and seen what difference that made, but it's a bit late for that now....next time.

And I agree with the general concensus that actually rebuilding the mechs with new parts is the only way to truly assure the least friction and most efficiency. I chose not to do that for my own reasons. My original question was whether or not the actual coils themselves could weaken over time. I didn't see how that could be, (I mean, it's a single piece of wire with about 2.4 ohms resistance....how much could that change even over 55 years), but thought I'd ask as there are some pretty smart folks out here in forum-land. If I'm understanding you correctly, there shouldn't be much change in the strength of the actual coil.

Thanks for all the responses - it's always educational!