My 1974 240D stopped glowing this morning. Is there a simple way to tell if all of a sudden the glow plugs crapped out or if it is a problem with the switch in the pull knob? Are there any other fuses or switches I don't know about? Thanks,

Brian

You can check loop glow plug filaments visually, will be obvious if burnt out same as lightbulb elements. And if one lets go then all others following in series wont glow. I've got couple of spare loop style glow plugs if ye need em.