Thanks guys! Sound advice.

So, I had checked the Pre amp Out and Power Amp In sockets and found at least the pre amp was working.
But! I just realised I made a foolish mistake. By not having the sockets (pre amp in & power amp out) screwed into the chassis they weren't getting ground.
So, next I need to trace for a signal. Heading to work first and then I'll get back to it!

Hi, I'm looking for some help repairing an amp!
I'm having problems with the power amp of an Acoustic model 120. The pre amp is working fine.
The amp powers up with quite a loud thud from the speaker. Also a thud on power down.
But then there is no signal from the speaker. I measured 65mV DC from the speaker terminals. I have checked all of the transistors and they seem fine. I also checked the electrolytic caps and they seem fine. I measured +44 VDC and -44 VDC coming from the bridge rectifier. And the same +/- 44 V on the collectors of the output transistors which are MJ 15024s.

When switching the power off, I hear the signal for a split second and a thud.

Any advice on what to do next??

Thanks!

Here's a link to a schematic of the amp.
http://music-electronics-forum.com/attachments/25116d1378895252-122.jpg