It's just the light in the photo. I'm not sure about which way the diode should go either. Both the top and bottom pics have the diode the same way only in the bottom picture one set of wires is connected to a different lug. I've now resolderred the wires onto the other lug so they both look the same. Unfortunately it hasn't made any difference.
 I will get a new diode to try here anyway but I'm sure that's the problem either as the kicker works  consistantly, just not in the way I think it should. Having said that does anybody else have this game and should the first ball into this kicker be held or kicked straight out? I'm only going of utube videos as a reference.