Hi Steveg,
Had the same problem with a badly adjusted lever a long while back. If they replaced cylinder but not the lever the problem would get transfered. Would be very suprised to find any brake fluid to be the problem. Besides it's not your problem even if it was possible. If it was me I would definetly carry on pursuing this. You would see some pretty major damage if a lump of metal had jumped in your wheel, disk etc, big enough to cause a large braking action. Missing wheel spokes or exploded disks should give this away. Perhaps you could get an independent motorcycle dealer to pressurise the system in reverse and push fluid from the caliper back into the mastercyl resevoir. Check the flow rate. Now remove the lever and see if the flow increases. If it does then the lever is wrongly adjusted. Don't change it as this is your evidence. Good luck mate.
Alternatley give your lever to a "mate", go for a nice long ride, if he craches you know what the problem was.......
