Low Pressure Shower Issue

Hi.

My very first post. I'm stumped. We bought a house and one shower has never worked well. All other fixtures have great pressure. It's a Delta faucet (single knob kind, don't know the model) with a pull-down diverter spout. Water comes out when you turn it on in a fairly small stream. Equal pressure on cold and hot. THere's not enough pressure to hold down the pulldown diverter, and if you hold it down barely a trickle comes out of the shower head.

I've taken the knob and ball thing out and turned on the water and LOTS of water came out through the valve with the guts removed. Good pressure there. After I put it back together it's exactly the same (except for the scratches )

I took the shower head off and it is clean. I took the diverter spout off and it seems clean too.

We did have a bathroom faucet clog with what looked like calcium/lime buildup. (in the aerator part).

So what am I missing? What could be causing this, and most importantly, can I fix it myself without either cutting a hole through the wall or destroying the thing in the process. Did I mention I'm not a plumber and have never plumbed?

--Matt

No one has even an idea??? Man.

Is this valve a pressure balance version? The spool valve might be stuck. If you take the showerhead off and open the valve, do you get a good flow? If not, then the easiest thing might be replace the cartridge. If you do, check the showerhead out carefully...something is blocking it. Somebody will have some other ideas.

I don't think this one even has a cartridge. It's not a pressure balance one. It just has a stem (that attaches to the knob) with hollow ball on the end with a series of holes that match up with the hot/cold incoming lines and the outgoing line.

Completely removed both the spout and showerhead so nothing is blocking either.


Thanks for the replies so far...