Valve problems

My bypass valve does not want to shut.

When the handle is depressed to switch operations it allows the water to escape out the backwash hose. When the handle is located in the proper place, lifted into the groove it stops the bypass and starts whatever function I had selected. Now that valve is not closing. I currently have the backwash hose looped back into the pool so it wont drain.

Can I DIY fix this?

Can a different valve head (Idk the proper name for this) be used? I have two other valve heads from other systems.

Can this be repaired in a shop?

What is the cost associated with replacing this part?

If this is your multivalve, it is usually repairable. Something could be stuck, the spider gasket could be damage or a spring could be broken. If it's just a shut-off or 3-way valve it may or may not be rebuildable. Some are, some aren't.

I think it involves a spring. I press down the handle on a spring (feels like a spring) But have to lift back up like the spring is not providing the resistance to return the handle. The handle itself appears to be riveted on. When you say "Repairable" do you mean: I may be able to repair? Or at a repair facility?

Yes to both. Most parts in an multivalve are replaceable, as long as it's a name brand. If, however, the walls of the valve are broken, repair is probably not likely. Whether you can do it yourself depends on you.