Advice for servicing a Scott Sub 10 [8 speed Alfine hub gear]
I've owned a Scott Sub 10 Alfine 8 (orange 2011) since Jan 2012. I've done 1600 miles and it runs very nicely indeed. Unfortunately I rode through a 'puddle' during the floods, which turned out to be 18" deep - it completely submerged the hub for 5-10 seconds. I bought a litre of the magic shimano oil for £60 from a shop which has since gone bust. When I opened the hub there was absolutely no water ingress and the internals looked factory fresh. I followed Shimano's servicing instructions to the letter. It's not difficult, taking about 2 hrs - a professional mechanic could do the whole thing in 30 mins.
The quote of £140 is very steep. Although the oil retails for £80, it is reusable - just leave it to settle and return to the tin. I weighed the oil can before and after, and I used 35gm - in other words there's enough for 30 services. The cost to a shop which regularly services Alfines would be £3 per hub. Adding 1 hour's labour would come to about £30. If you do your own servicing, don't degrease the hub in solvent - the drive side bearings are inaccessable without buying an expensive tool, and thin oil, like ATF, will not keep them sweet for long. Read the net for loads of people who've done this and now blame Shimano. Regarding 8th gear: this has the most cable tension,so if it's an adjustment problem, it needs more tension. Also look out for a rusty/ bent cable. Finally, if there's dirt behind the casette joint it might limit movement.
Try removing the cassette joint, cleaning it and regreasing the cable while your at it. I'd be quite happy to talk you through the service, but I don't want to publish my email/phone. I'll keep an eye on this page incase you want to contact me again.