When I turn on the water, then go to pull the knob for the shower, the water still comes out of the spout and just about half of the water comes out of the shower head. Do I need to replace something inside?

I need a little more information before I can help. :-[ Is there a knob on the spout that you pull up or is the diverter in the valve on the wall? What make faucet? How old? Get on back to me and I'll answer ASAP. Tom

Thank You for your help... the mechanism is about 12 years old (original equipment). The spout has a knob on top that you pull up to stop the flow from the spout and re-direct to the shower. It is a single control for the water (vice separate hot and cold knobs) that you pull and turn left or right to control the temperature. The brand is Moen (Stanadyne).

You have a few options here. Though this has nothing to do with your problem, we use Moen faucets on all our new construction and I have nothing but nice things to say about them. There are two types of tub spout diverters. Metal and chrome over plastic. To tell the difference look under the spout next to the tile wall. Is there a small square opening there? If so its plastic and can be removed by loosening the allen head set screw up there and pulling straight out. The metal ones unscrew. You can now check inside to see what's stopping the diverter from shutting off completely, or since they don't cost a arm and a leg you can just replace it. Hope this helps and thanks for using us. Tom