Bath to Shower Lever is Stuck!!!

My  lever you push down to have the water come out from the bath faucet to the shower is stuck! I can pound it down to make it work and use pliers to lift it back up.  Is there a way to fix or lubricate this so it works better without changing my how faucet? Does anyone have any ideas what will work?

try spraying wd-40 into handle opening on tub spout then u will have to pull up and down a few times. ps, use the straw that comes with the can to get it oil into opening.

I agree, when in doubt W-D 40 first, hammer 2nd