Break off the tabs with a pair pliers. You will
then be able to use a small screw driver to pry off the back cover.
I used a needle nose pliers to carefully break
off as much plastic as I could from the bottom. (Shown by the arrows.)
I carefully broke away the the plastic from the
top with a needle nose pliers.
After I removed as much plastic as I could, the piezo disk was easy to remove from the remainder of the plastic. I did
this with all the piezos with the same results. No ruined piezos.
Play Rock Band, GHWT with your electronic drum
kit