This afternoon I was cleaning my car, for what ever reason I turned the key all the way to the right with out starting the engine. After a minute or two I started to smell something burning; the glow-plug fuse on the firewall was melting. The fuse it self stayed in tact but the screw started to melt out of the plastic holder. What is going on here, this is not the first time I switched the key all the way to the right with out starting the engine?

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).