TSPP was my first pinball purchase last year. I had the same problem. One solution is to bend the metal "fork" on the switch up a little. But after time this bandaid will fail. You can access the fork by taking off the upper playfield. Or you could solder in a new switch from below the playfield. Order from here http://www.pinballlife.com/index.php?p=product&id=197
They are only four dollars.
If you search TSPP VUK garage problems on pinside there is a lot of info on this problem.