[thstone]

The justification for replacing the RMS is that the rubber is now 15 years old and has probably lost much of its elasticity making it a prime suspect for a possible leak in the future.

But as you mention, any type of invasive procedure creates the risk of introducing or creating a problem where there was none previously.

If it were me, I'd replace it while following Gelbster's advice regarding JFP's recommended best practices.