[Arran]

 There isn't anything wrong with Sprague Orange Drops in and of itself, but the installation was rather sloppy, the electrolytic placement seems just as bad. I would bet that whomever did the work probably just clipped the old caps out and tacked the leads of the new ones onto the old terminals without doing much else, so they will probably fall off within a few years. You could probably go in there with a soldering gun and remove most of them within 10 minutes. As for the bias cell, that really has to be there for the set to work properly, especially if it's on wiper of the volume control, if you rewire the holder so the polarity is reversed you can use a modern watch battery in it's place, or use the old cell as an adapter for the new watch battery.
Regards
Arran