I don't seem to have a lot of luck. I managed to fix a speed issue on an RT-707 reel to reel and then I realize that neither meter lamp is working. A quick check confirmed power and that both lamps were shot. This nice little co-axial frosted lamp might be available somewhere, but in this town of one million a check of all the usual sources turned up nothing.
Since necessity is the mother of invention I started looking for a substitute. What I found were replacement Xmas lights rated for 6 volt AC. The meter lamps were getting 7 volt AC. I thought of using two lights rated at 3.5 volt in series but I felt space inside the meter might be an issue.
Anyway, I added a small length of wire to one of the bulb leads and added shrink wrap to that. Then I folded the lead around itself to make it into a co-axial configuration and soldered it back into place where the original lamp was. It fits perfects spacewise and appears to provide about the same brightness as the original lamps. I don't know about longevity but at 99 cents for a pack of 5 bulbs I don't have a big investment in it.
I attached a pic of the original lamp, the modification and the lamps when done.

I wonder how many milliamps are being drawn?? :scratch2:

An 8v/100ma axial lamp would also work. :thmbsp:

http://i86.photobucket.com/albums/k98/dgwojo/7v_100ma_Meter_Lamp01.jpg

The draw is 89 milliamps. I would have used an axial lamp had there been any available locally. There are only two electronics supply stores in the area (pretty sad) and they don't have a huge selection of the kinds of things we find in these old stereos.

You can frost that replacement lamp yourself if you want to get closer to the original lighting effect... crafts stores sell glass paints, look for heat-stable white frost finish.

John