The bricking is fixable. I have fixed that on all my old Ballys.

It is when the drop targets are hit and they do not fall. The flexibility in the target is what makes them brick. Before they have a chance to fall, they bounce back onto the lip keeping them up.
I found the fix on RGP from a post there about a year ago. The fix is to fill the back of the drop targets with epoxy to make them more rigid. Some have used small finish nails before the epoxy to improve even further. However, I have found that isnt necessary. I found the 2 part epoxy for plastics at the local Ace hardware. I then paint the back of target to match the color of the target after epoxy is dry. It will fix about 95% of the bricking problem. To get close to 100%, cut the springs about a 1/4" to make the targets pull down a little quicker. On my old Ballys, the bricking issue is 99% gone.
I played a Metallica at my buddy's place and the new Stern games brick as well.