Of all of the very early meters, the Miller design was probably the most reliable. It is also one of my favorite designs, aesthetically. While they made thousands of them over the 20 years of production (late 30's to the late 50's) both meter and parts are starting to get hard to come by.
I always enjoyed working on this meter but now that parts are becoming difficult to find it has taken a lot of the fun out of it, sorry to say.