Longtooth - my experience in removing the bezels I would have described as Naj has, so I will try it differently.
Looking at the back of the instrument, you will see that the crome bezel is crimped onto the instrument body. If you take a small screwdriver, you can 'uncrimp'/ pry open the bezel. If you do this to about two/thirds of the circumference of the bezel (and so also the instrument), the bezel will come off. You can straighten the bezel quite far without damaging the way the bezel will look from the front when you put it all back together again later. From the back, you will always be able to see that the job was done by an amateur without the proper tools (I am sure the instrument maker has some sort of specialized handy tool to crimp new bezels onto the instrument).
I did my tach and my center cluster instrument this way. From memory, I believe that the center instrument bezel comes off easier, since the crimping is not all around but only in certain places. From the front, it is not possible to tell that the bezels have been off the instruments. You have to work a bit carefully though. The difference in the appearance after cleaning the glass on both instruments was tremendous. I knew it would be, because I could always tell the difference between how they looked before with how they should look, because the previous owner had a brand new (KM) speedometer installed not too long before I bought the car.
Good luck,
Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic