Some of my BK's trough switches (top & bottom) were occasionally iffy even after the usual business-card-method cleanings. Even with a drop of tuner cleaner spray soaked into the card. Very very aggravating. Saw a tip in Pinside someplace about using something a little stronger like Mother's Mag polish so I rubbed a tiny smidgeon of that into the card and wiped once and then ran a strip of thin cotton sheet thru them several times to be sure they were totally clean, that did the trick. Worked on a EBD drop switch too which sometimes failed to register. Has anybody put brand new leaf switches in BK and *still* had them be glitchy? I suppose switches that are held closed like the trough would cause more issues than ones that are only closed momentarily since they need to reliably be closed whenever they need to be read by the game as closed or open, but my Stern Lightning's multiball holes and troughs have never once failed like this. Makes me wonder maybe it is just a difference on how much extra-stubborn 'gunk' happens to be on them. Unless the flashing really is worn thru of course.