Evan and I looked at this. First we ran the gumball test. The gumball itself seemed fine but there were trough problems.

Eventually we discovered that one switch was sticking and another had its wire broken off. We slightly bent the wire to clear the slot and replaced the broken wire with a new piece. The trough was still behaving weirdly with the ball bouncing back to the outhole. We bent the switch further up so that it held the ball from bouncing back and that seemed to fix it.