I need simple instructions about repairing a leaky Moen single handle shower faucet.?

Question

The faucet has On/Off pull handle with rotation to right and left to regulate hot/cold. It's begun dripping and is sometimes difficult to turn off. I suspect the faucet is at least fifteen years old, possibly older. We live in an area with very hard water.

Answer 1

Moen has only replacement faucets which are  guaranteed for life.  The one you have is the older brass model which is not under that guarantee.  It is cheaper to go with a new unit.