@rip-the-jacker
Not sure about how much that might cost to fix. I did just fix a similar issue myself on an old amplifier I had though. Crackly and distortion on the volume and other similar knobs. I opened it up, and cleaned all the contacts with isopropyl alcohol. Cost me a tenner for the bottle many moons ago, and have used it on all sorts of electronics since. Worked a treat. So would be my first port of call. If it doesn't work, I cannot imagine replacement faders would actually be very expensive, and if you have already opened it up to try cleaning first, I'm sure you would see they would be a doddle to replace. Much like replacing a crossfader.
I suspect something like this would do the trick:
https://www.ebay.co.uk/itm/ALLEN-HE...036506?hash=item46584b3cda:g:RH8AAOSwfC9XPae8
Looks like you need to use a soldering iron though, so if you're not up to that, you could either find a local electronics dude to do it, or send it in to A&H. The soldering itself should be pretty easy though. The main trick is less is more. The less solder you use, the cleaner it looks, and so long as it's solid, should be fine.
Either way, it shouldn't actually cost that much to fix. So £80 is probably in the right region. Whether that's a price per fader though, I wouldn't know. Could always call them and ask?
In the meantime, if your getting it cheap, then happy days. And you will still be able to use 2 and 3 in the meantime, so still as many channels as you currently use, but with all the effects the DB2 brings to the table.