Looking at your HP427A voltmeters I was reminded of my Philips PM2454. As an AC millivoltmeter it's of a different kind, but it does have a nice, big movement, too.
So I decided to take a closer look at it and create some more Philips pr0n.
Already switched on:
Innards:
And, of course, the range switch:
The 'lytics check found one deaf cap in the power supply, the rest were exceptionally good:
The pilot lamp wasn't dead - there wasn't one at all. As I had none that fitted, I removed the stern contact from the socket, sleeved one leg of a 3-mm LED and slid it through that small hole. The other leg was bent to make good contact with the outer metal tube. The LED is now supplied from DC. Since the cap is not very transparent, I let it run at 20 mA to get enough light (sorry for the lousy pic):
The PM2454 is mostly in agreement with my HP34401. I didn't bother to calculate whether it's outside its spec (and I also don't know about the HP - AC references are much less common and much more expensive than DC ones).