Camchain Tensioner

I've not examined my camchain tensioner yet, but when I saw this rare beast on American eBay, I thought I'd better snap it up! I've seen some attrocious ones out there, so this is a great find.
WORN TENSIONER:
I installed my NOS air filter tonight and noticed that it was slightly different to the original one in that it had an extra "wing". I'm guessing it was designed to deflect any water from the rear wheel and is no doubt off a later model than mine. Nevertheless, it fitted without a hitch. After fitting the air-filters I adjusted the throttle cables to ensure the throttle was opening both carbs at exactly the same time.