oil temp/clock gauges

I've taken the oil temp and clock out as I wanted to change the bulbs to blue LED's to match the other instruments, shock horror they are sealed units (its a TF, F's aren't apparently) with internal LED's already.
I have a mate who will solder new ones in but how do I open the gauge up, is it a case of gently peeling the bezel back to get it off, I've looked at the "How To" but that shows the gauge innards already out with no explanation how.

The gauges have to be prized open. Also its a good idea to check the polarity of the connections to the led's as you have to solder them on the correct way round. If I remember correctly, they will be standard 3 volt LED's not 12 volt as you would put in your dashboard instruments and switches.
Suggest you buy a couple of second hand ones to butcher, then you can always revert back to normal if you want to sell the car on as original.

Sundance