I think Frankenstein trough will be considerably different, but basically this is what Buzzbee is referring to.
I think Frankenstein uses regular switches to account for the balls in the trough.
Williams/Ballys, like Indiana Jones and my STTNG (I replaced these boards this morning) use optos (beams of light) to account for the balls.
WP_20140524_001.jpg
trough2.jpg
I would imagine this is more of a switch issue than a board issue personally. Then again, I don't know shit for the most part either, lol.