This may sound strange but what is supposed to happen when you hit the drop targets? Mine don't score, yet they reset at the end of the ball. Do you get any points when hitting down each one? I think mine never have awarded anything.
I have a switch 29 problem (right hand drop) - will check the opto, but it has made me wonder how they are supposed to function!
From http://pinball.org/rules/earthshaker.html :
"The three drop targets are located near the bumpers at the base of the building. Hitting all three targets awards the current point value, resets the targets, and increments the value of the Jackpot.
The initial value at the start of each ball is 50K, and increments by 10K (up to 100K) each time the targets are reset. The "BILLBOARD VALUE 100K" Match-up award sets the point value to the 100K limit.
Also do they only reset at the end of the ball?
Can anyone help explain?