I replace mine. There cheap enough, esp from Carolina bike/trike. I inspect my thrust. I do mine every spring regaurdless of mileage. Usually no more then 15,000 miles. This is my 1st season on a CT but not nearly the miles I should have so far.

I'm with you Fudgie... I buy my o-rings from carolina bike... It is much less to replace o-rings than to replace splines.. The alternative doesn't sound very appealing to me... To each his own... I also run a C/T and I inspect relube and new o-rings every 15k miles. All of my o-rings that I have taken off in that time frame have looked good but I just replace them...