I'm pretty sure Moen stamps the model number on the back of the faucet,
but unless you're really agile, you may need a mirror to see it. On
each of mine, it is on the back of the upright, facing the wall. Once
you have the model number, give them a call.

Ken wrote:
We have a single handle Moen kitchen faucet with a sprayer hose on the
side of the faucet. Since we bought the house used, I have no
paperwork about the faucet giving model etc.

The diverter valve inside the faucet seems to be sticky and does not
work properly when the sprayer hose is turned on unless we turn the
sprayer on and off several times quickly.

Are there any servicable parts inside the faucet or would just taking
it apart and cleaning help?

I am a novice at such things and don't want to take it apart if it
won't solve the problem.