Originally Posted by
RothwellAudio
What's access to the underside of the board like? If it's a pain in the backside I'd be tempted to leave it alone as much as possible. The flying leads are attached by "wire wrap", which was common with Japanese equipment of that era. It's actually a very good way to make a joint but impossible to remove and then re-wrap.
The usual "re-cap" involves replacing just the main power supply reservoir capacitors. If you want to go further you could replace all the electrolytics, though there are probably dozens of them.
I'm not sure about the orange gunk. Yes, it could be residue from the original caps which have since been replaced.