Intermittent Glow Plug Light '84 300D

[lldanj]

My glow plug light is acting up lately. once in a while (cold/wet mornings it seems) it doesn't come on. When it doesn't come on, the car won't start (i.e., glow plugs aren't coming on either).

I open up the glow plug relay box and loosen and tighten the screws holding the fuse strip, jiggle the two wire connection plugs and voila! we have pre-glow houston!

what's up with that? I can't figure if it is a wiring problem or if it is a problem with my glow plugs. is this a common symptom of one or more bad plugs?

thanks for the help.

Dan