Regarding the debate about "filing switches" and what one should use, with the wisdom about not ruining your fragile gold-plated low-voltage contacts in mind, may I present some anecdotal evidence toward a possible DIY solution that might work with discretion:
I was recently finishing a Time Fantasy to take to a show. It has 5 lane-change rollovers. Two of them were flaky, in that they worked about 75% of the time. I'd used all the previous tricks: fiber business cards; crisp dollar bills; the same soaked with alcohol (which I have found really gets the grime off contacts but makes the card/bill self-destruct), etc.... but in all cases the fix only lasted a few dozen plays if that.
With time running out before the show I finally decided to buy new switches, but they were out of stock. ARRRGH! So as a "well crap, what have I got to lose" desperation experiment, I made my own burnishing tool to be more aggressive than a business card, but less than a file.
I used an old flipper bushing gap fork tool, some double-sided tape, and some thin 600grit sandpaper (from a modeling kit). I laminated both sides of the gap tool with the sandpaper. Passed it between the switches (turns out the flipper tool is the perfect length, thickness, and durability for cleaning a properly gapped switch). There was some slight metallic residue on the sandpaper to prove they were "cleaned" but did I actually ruin them? I took some "spare hackable parts" with me to the show just in case.
But my cleaned switches lasted the entire show (and afterward) trouble-free! One was 100% fine, the other acted up about halfway through the show but with another quick pass of my "desperation cleaner" was fine again and has remained so. I've since used it on a few other switches that were inconistent trouble points in other games with similarly good results.
Again, I wouldn't necessarily say this should be the first go-to method for cleaning... but if you're reaching that "line of aggravation", as your last attempt before replacing a switch you can't obtain or replace easily, or for troubleshooting a project to determine what's actually broken or needs to be bought, this method might be valuable.