Well, as I expected, the underside of the Marantz 2130 is covered with circuit boards. Combined with the RF and IF circuitry on top, there is quite a lot of stuff in this tuner. I started examining underneath the tuner on Saturday night.
Above is a closeup of the MPX board. In there is a Hitachi HA11223 mpx chip with external switching transistors. The big modules on left are 38Khz subcarrier filters...those need to filter down to 22Khz. The MPX board uses a pilot canceler implemented with discrete circuitry to remove the 19Khz pilot from the output.
Above is a closeup of the power supply board. There are 3 heatsinked semiconductors on the right, and one in a larger heatsink on the left. In addition to the fuses on this board, there is a fuse on the case.
Above is a closeup of the buffer board. Both the mpx and the buffer feature single 4558 output IC's and relatively large electrolytic capacitors. I worried a lot about the black dot on the large capacitor near the center of the photo. I wondered if it had been painted on and in fact it's hard to tell as there is no other sign of leakage than the back mark and a slight depression where it is. If it was caused by having a leak once, it appears to be completely sealed now. It turns out to be a capacitor in the oscillator circuit, so I'm not too concerned about it. However, the entire tuner did have what I often consider the "bad capacitor" smell. I doubt that it all came from the one above, but it might have. I washed and dried the entire exterior case over the weekend, allowing each piece ample time to completely dry. I wiped bare chassis metal, and transformers, and accessible parts of the scope. Everywhere I wiped in picked up some brown, perhaps some previous owner was a smoker though it doesn't small like smoke as such, it smells like bad capacitors. All the cleaning reduced but did not eliminate the smell.
I was unable to find in the manual how this is supposed to be done. Perhaps the wire originally was stiff enough that it didn's sag in the middle, or perhaps (and most likely) the wire was surrounded by a piece of heat shrink either from the dial side or the other side (the wire was originally attached to a wire clip on the cover of the RF unit).
Heat shrink might be the best solution, but it would require at minimum unsoldering the lamp without damagin the plastic, a very tricky operation. That might have been why Marantz Service didn't fix this. Perhaps the original heat shrink got damaged and was jamming the dial, so they just removed it, and didn't bother to replace, not realizing that the above problem could occur.
I came up with a fix that did not require any soldering. I cut a nylon wire tie and placed it across the valley of the inside of the tuner from RF cover, where the now unused clip for the lamp wire is, over to the dial, where it is jammed between the circuit board and the dial plastic. As the indicator moves across the dial, the wire tie supports it in the center about an inch from the circuit board at worst case (shown in picture). Most of the time, it is much higher than this. It took about an hour of tweaking to get it this good. I still worry about a number of things, including the possibility that over time the vinyl covering on the lamp wire will wear off rubbing against the nylon tie. But I suspect that won't happen fast, if at all, and hopefully just disable the lamp or blow a fuse.