Just a quick note about a fairly common problem with the old cars with the "torpedo" fuses (any MB well into the 90s if not later): Sometimes the fuse strip material, particularly if it's aluminum, will oxidize to the point that it's no longer making a suitable contact with the brass connections in your fuse box. If you ever lose functionality of a circuit but find that the fuse is not blown, just rock it back and forth with one finger, twisting it on its axis. I've had this be the cure more times than I can say. Same thing happens to strip fuses such as the 30 amp blower fuse in w124/126 cars, and the 80 amp glow plug relay fuse in 116/123/126/124/201 diesels. In these cases, loosen the screws slightly and retighten. This will also reveal any hairline crack that is not otherwise visible, particularly in the 30 amp fuses. For those that are more adventurous, this same concept also applies to any wiring junction. Loosen and retighten the fastener, or touch up with fine grit sandpaper. Particularly on chassis grounds.
Good luck!