Steve,
No words of wisdom, but a question. WD40. Does WD40 eat rubber? If so that is your problem. Use kerosene for those times that you have to clean your chain. Since using Maxima Spray Chain Wax I have never had to clean my chain(s). The can says to apply sparingly, but douse it up and wipe off all you can. This will clean the chain. The Maxima Spray Chain Wax conditions the chain's o-rings and adds a bit of cush to the contact points of the final drive as well. WD40 I just don't know enough about. I do know that I would never and have never ever used WD40 to lube any chain. bicycle or motorsickle. 7100 miles is way too short of a life for a chain. I average 19 thousand miles on a chain kit (front sprocket, rear chain ring and chain).
Brent at newspeedmaster.com sells some nice gold plated chains and he sells the sprockets too. Or Triumph sells the kit for $219.
