I wouldn't use WD-40 or any such spray onthebelt--can more rapidly cause deterioration. OK for a tiny bit of anti-staticspray.

As for best belt life & effiency--

1. Tighten by the book -- Then a "Hair" looser. It WILL work
2. (Got this clever inspitation from another thread) Check the belt position, on the tail
gear, while running.(Make sure Heli is strapped down- Be careful) If there's a tendency
to pull to one side or the other, loosen the tail
gear case and rotate it very slightly to the Rt or Lt, until belt stayscentered.Remember,
there's 90 deg twist to the belt so there will be a tendency to pull to one side. This slight
adjustment will help correct the problem. No need for a flanged idler & more friction.

Lloyd