<< How can I check and/or service the diesel injector? I know virtually
nothing about diesels, but the injector is external and easy to get at. >>
Don't assign the problem to something just because it is easy to mess with.
Could be cold weather fuel jelling (do you run #1 diesel?). Briefly cracking
injector lines will clear air blocks. Small amounts of water in the fuel are
also nasty to deal with. How old is your fuel filter?
Having persistant problems might mean you have a loose or cracked fitting in
the system. Could be hard to find, so good luck.