I want to replace the stock tuners on my MIM J-bass with some descent tuners. The stock tuners aren't very stable and lack precision. I was thinking about buying Schaller, and more specific these ones: http://www.thomann.de/thoiw7_artikel-171262.html Is this a good idea and are they direct replacements? oh, and do they come in packs of 4? Is it 59 euro for 4 or for 1 tuning peg?