I've not heard a C26, but I was/am pleased with my C28. I especially like the separate L&R bass/treble and lighted selector points. However, I now use a C33 as it has a noticeably lower noise & hum floor, is much more versatile, (especially for recording) and the 5 band EQ is more useful to me than separate L&R B&T. I have 2 C33's and both are outstanding. I use one as an integrated in my office (the monitor amp is fairly amazing), actually, and the other with an MC2205 at home. In general, as far as analog goes, newer is usually better up to the C33. The C32 had some ribbon wiring issues, otherwise similar to the C33. C29's are somewhat rare, C28's VERY common, so I don't think they will go for much more than a C26, which had a fairly low build. If both require appreciable work (greater than $3-400 each, and expect $200 with S&H to be the MINIMUM per unit), then you are far better off selling what you have and investing in a better unit, that has been serviced (C29, C32, C33). I picked up my 2nd C33 for $700, with an original Mac box, and it is near perfect, though that is a very good price. $1000 is more typical. A fully serviced C28 is worth maybe $600 on a good day, an unknown unit maybe $300-350. So if you take the $200 you would have spent (min) ea on a C28 & C26 repair and get $300 for the C28 and $250 for the C26, you're already at $950, and would end up with a much better piece.