[] Refitted now thoroughly cleaned front indicator lenses. Output is vastly improved now there are no longer insect nests in them.
[] Removed non-functional windscreen wiper mechanism and established the cable has seized inside the guide tube. Have left it soaking in penetrating oil overnight.
[] Rediscovered the fact I still need to properly wire in the new fuse box.
[] Answered the question of whether the dash needs to come out to inspect and if necessary repair any wiring.
That crusty bit of terminal strip is in the main live feed to the ignition switch. Oh, and I can see another terribly done crimp terminal on the ignition switch - through which every milliamp for everything aside from the headlights flows.
Needs properly sorting, especially given the "minimalist" approach to fusing in the car (two fuses total originally).
Should be a good opportunity to swap the dash for one that's not cracked on the top at least.