I'm a newbie to this site and a complete newbie to plumbing. I want to learn how to fix things on my own. The shower head in my bathroom drips continuously when the water is diverted to the tub spout. Also, when the water is diverted to the shower head, water also drips from the tub spout.

It's an older setup. There is three handles; left for hot, middle to divert water to shower or tub spout, and right for cold. Also, water drips from the right (cold) handle when it is on.

What are the defectie parts here? How difficult is it to fix this myself?

Thank you.