In the tub, when the shower diverter is pulled, a large amount of water is running out of the tub spout, lowering the water pressure in the shower head. In the past, the "normal" or expected amount of water came out of the spout, but this amount is much larger. Is there a way to replace the diverter? Is it possible there is a different problem?

Before we can help we need more details. Wher's the diverter located? On the spout or is it a center knob in the shower valve? Tom

The diverter is located on the spout.

A diverter spout is so inexpensive that it's cheaper to replace then to hassle with it. They can be purchased at most hard ware stores. Regards, tom