Removing the body was easy enough (Electric Nose provides a good guide to removing the body on Heljan 47/57s).
It was soon clear where the lights were located and that they are evidently just plain grain of wheat style bulbs as indicated in the photo below. The 'red' tail lights are the result of red lenses in the body, with the plain light being shone to them through the holes marked in the photo. There is, therefore, a further bulb hidden somewhere out of sight.
What was not so clear was how to gain access to the two main bulbs secured in place below what would seem to be some superglued plastic.
The plastic is however not stuck down by anything substantial - and I found that by inserting the edge of a small chisel in the gap between the chassis and the plastic was more than enough to lift the plastic lid off the chassis.
The sight was somewhat surprising:
On careful inspection it became clear that at some point in the manufacturing process my poor Heljan 57 came very close to having no 'white' lights at all - look at the damage to the black cable (zoomed in the photo above). In fact, with the core of the wire exposed, it is possible that the actual chassis was almost 'live'. I've also just realised that only one end of the loco has sprung buffers - is this usual??
Returning to the case at hand, it is therefore quite clear how to improve the lighting - simply swap out the bulbs for superbright white LEDs.
The actual fitting of these will have to wait until next week though - as I will, at the same time, add the DCC decoder to the loco.
Watch this space. Hope this is of use to people. Would also appreciate any thoughts on things so far: namely the half-present sprung buffers?
