It came apart very easily actually. You can tell it was designed to be maintained.

The original coil and resistor:

So without these in, it's time to think about hooking the needle up to a servo motor.

Currently, as this is in the proof of concept stage, I'm going for the cheapest options. I needed a servo that's small enough to fit behind the dial. This is a little tricky as most servos seem to be too large. And at this point, I'm not really sure how I'm going to link it up.

A cruise around eBay and I've ended up with a 'Tower' sub-micro RC servo. I've never done RC before, and apart from a university project a few years ago, I've never used an RC servo in a project.

Time to do some research on how to drive RC servos then!