09-02-14, 08:02 AM
Before you do anything with the master cylinder, have you tried cracking the Venhill fitting at the MC end to bleed any air out of the system at that point? Obviously you need to prevent any fluid coming from the joint from squirting onto the paint or swingarm finish. 
Rear MC seal failure isn't something we hear of often. If you're still not happy with brake lever feel after trying the above, you might find it cheaper to buy a used one complete off ebay.
Rear MC seal failure isn't something we hear of often. If you're still not happy with brake lever feel after trying the above, you might find it cheaper to buy a used one complete off ebay.