Originally Posted by tabetha

The easiest way to check glow plug supply is just connect a metre/test light onto the supply at the glowplug when some switches the ignition on, it should obviously light to show supply is present and go off after set time, listen carefully and you will hear it click.
If really cold, you are much better off giving a few goes 2/3 on the glow plugs before trying to start.
Have you drained off the water from the filter head recently via the small bolt on the underside ?
Also try some millers diesel cleaner and if around your area some bio diesel.
It might also pay to see if it still has fuel pressure at the filter head as the diaphragms are very prone to splitting on these, but filter heads are cheap.
Just push down plunger, if it has pressure you will feel it, if not you will feel it build up after many preses.
This must be tested before turning over though.
tabetha