Anyway, on testing it, I’m only getting sound out of one of the two pickups (bridge, nothing from neck). How do I test the pickup itself to make sure that it’s good? Is there some kind of multimeter test I can do or summat?
It’s a simple process to test a pickup. Set the multimeter to the ohm setting and touch its red test lead to the pickup’s primary lead (hot) and touch the black test lead to the pickup’s ground wire. You should get an ohm reading in the kilo ohms.
A simple first step is to make sure that the volume is turned up for the pickup. I would then use a multi-meter to ensure there is continuity (using the multi-meter ohms setting) going through the pickup coil. If there’s continuity there, I would check the volume knob for the pickup between the hot/ground. Sweeping the knob from full volume up to down should increase/decrease the reading on the multi-meter. Good luck with your diagnostics!
I would review your real wiring against the diagram 2 or 3 times to ensure it is actually correct first.
Then visually check every solder joint.
Then, check continuity across every connection from the pickup leads to + and - on the jack and jack to ground.
Check that the pot on the neck is OK and you can sweep the ohms from 0 to whatever the value is.
Also as stated above, check continuity across the pickups, they should be close to the same value.