After letting my '86 560SL sit too long (about 4 months), she no longer wanted to start last week because the lovely ethanol in our gasoline likes to attract moisture and the 30-degree F temperature swings where I live gave the ethanol plenty of condensation to attract.
Today I drained the fuel tank, replaced the fuel filter, purged the fuel lines, blew the crud out of the injectors with a bicycle pump, and cleaned the fuel distributor's intake screen (which was so clogged I couldn't blow through it in either direction).
The good news is that with all that work, she started right up.
The bad news is that one of the 5mm allen-headed bolts that holds the injector retainers rounded out. Two different Allen sockets and wrenches just made it worse. The solution was to break and mangle the injector-retaining spring-thing until it could be rotated, thus loosing the Allen bolt.
As a Macintosh computer user, I am unable to utilize Mercedes' glorious EPC-net Online parts reference website at
https://epc.startekinfo.com/epc/home.jsp. If you are a subscriber, and can spare the time, I would appreciate a lookup of the fuel injector retaining clip (I have no idea was the correct term is for them) and the short Allen-headed bolt that affixes it to the intake manifold. If needed, I can post some pictures.
Plan B will be to call the Mercedes Classic Center.
Thanks in advance!