NSM amplifier 76M

Hi
I have a problem with the 76M amp and I am not getting any sound. I got a lend of a 76M amp from another machine and fitted it to my own and the sound worked so the problem must be my amp and not the cartridge, remote or wiring. My amp is fused but the fuse is fine. None of the components looked burned out and I don't see any loose connections. What are the most common or the usual things that could be faulty with this amp?
seancalla

Hi
I have been going through some of the components but haven't so far found anything. I know on some of the more modern machines such as the Festival or City the output transistors can fail. I was just surprised the two pcb's in the 76M were not working in the machine I have. For the more modern machines I have the circuit diagrams and procedure for mA adjustments when replacing output transistors. But for this machine I don't want to change any of the transistors as I have not the proper procedure for adjusting of the milleamps after changing transistors. I have a schematic for the 76M but not a list of parts and specifications. Like every other jukebox there are fairly common faults with various components so if anyone could advise it would be great
seancalla