Hi Nino, It's a day later and I have not been able to work this one out. .... On balls 1-4 it's supposed to pay out 2X and then on ball 5 it gives up 4X. ... but it just pays out 4X on every ball. ... I thought it may be a game adjustment but couldn't find it. There are 2 relays which seem crucial..The 2 X bonus relay and the 2X Control relay. These are on underneath side of playfield. When the bonus goes off, the disc seems to count off the amount of bonus, and these two relays seem to be responsible for 2X and also 4X  (but I can see no mention of 4X anywhere on a relay or anywhere else.) I cleaned and checked the contacts on both these relays. .. no, I don't have a schematic.... A small but annoying problem which is between me getting it all right or not. ... this is someone else's machine and it'd be nice to hand it back 100% and not 95%....