Silver box repair is replacing every single electrolytic capacitor with new, cleaning any leaked electrolyte, and soldering jumper wires over any damaged/corroded traces. Some are in good enough shape that it's easy to repair. Some are so heavily damaged from leaked electrolyte that it becomes a challenge to repair satisfactorily. You won't know where you stand until you pull the cover off. I've had a very high success rate repairing the silver boxes, it just takes time and some soldering skills. Once repaired, they work very well, you'll wonder how you ever lived without it.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)