Moen "Shower only" no pressure problem

[Our Time]

Help!
Our house is now 10 years old and seems to be quietly disbursing plumbing attacks! The Moen "shower only" unit turns on with no problem except there is no pressure. The hot water is turned ALL the way up in order to get hot water. Trying just cold made no difference in pressure. We do not have the fancy style positemp or Moentrol...just the plan old fashion shower kit. I read through the complete thread on what seems to be the same situation I am having however; I am not sure if my problem is a pressure balance spool, bad "o" ring, or bad cartridge. The Horror stories on removal of any of these items have me nervous since I am female and strength is not one of my best traits. What would be my simplist way to identify what the problem is and any good suggestions on the fix.
Thank you:

 

[Jadnashua]

Unscrew the showerhead and turn it on, if you have good flow, there's crud blocking the showerhead.

most of the single handle valves do not have a volume control like on a sink...it's either full on or full off. you only get to adjust the temperature.

Are you saying that there is no hot mixed in at all until you turn it to max?

How old is the water heater? There was a period of time where the dip tube (a plastic pipe designed to direct the incoming cold water towards the bottom) was defective and the eventually break up into little pieces that clog up valves and showerheads. If you have one of those, that may need to be replaced. It would show up as white flecks. If you put some in some vinegar, they don't disolve like lime deposits would.

 

[Sponsor]

 

[Our Time]

Thank you for the quick reply. As for the hot water, Tank was just replaced in November. The shower worked just fine yesterday. This morning it was limp. When you were talking about the plastic pipe, did you mean I will see white flecks coming through the shower head? I would not know if I have the plastic pipe design but sure do hope not! I will try the CLR for the shower head this evening...and will also see if pressure is back. Thank you very much for the help.

 

[hj]

IF you do NOT have a Positemp or Moentrol, then you DO NOT have a pressure balancing spool. We would need a picture of the valve body itself, not the handle or cover plate, to decide WHAT you do have.