The button on my gear shifter gets stuck, and I have to pound it with my fist to

WD- 40 would be the best with straw attached wash it out well while working button.

I agree with wetry

This is a common issue because the plastic around the button starts to crack and cause the button to jam, or the shift-lock cable is jamming because the release button is jamming. I always replace the knob if that is bad or un-jam the release button to fix it, but you can give the WD-40 a chance first. Let us know if that works.