The Radical I was working on came in with a burnt GI connector. Replaced that. Lightbox still only half lights. Continuity testing from the transformer onwards now gets the the insert GI relay. Broken solder joint (several actually, both the relay coil and one side of the normally closed contacts). Fixed those too and the insert lights correctly and has flashing effects now too.

The playfield GI relay also had a broken solder joint, but on the coil rather than the normally closed contacts so it was less noticeable - no flashing effects but the playfield lit correctly once the burnt connector was replaced. Fixed that soldering and the playfield lights correctly and has flashing effects.

The Pioneer I've got had a range of issues with the tilt circuits. I'm not sure if it was tilting incorrectly for the previous owner or if they just didn't like tilt being enabled so it was disabled... by removing the tilt bob. Refitted that, still didn't tilt. Bit of hunting and they'd also bent the leaves on the tilt relay switches so it doesn't latch on and tilt the machine. Adjusted those and it now tilts, sometimes. I need to do more hunting.