the problem in that unit is it is made uf of single board, right?...so unless you have found the component in trouble the way to isolate the problem is too hard.
is the buzzer on when those leds are litted up?...
i have solved my problem before in that kind of machine by trial and error, i have tried removing and testing almost all the digital IC's on the board before i have identified the faulty component...unfortunately, i have'nt bring with me my detailed report regarding the troubleshooting when i transfered to my present company...so i could not give you the exact part number of that particular component...
but just try it though, analysis and luck...combined..