300cd-no crank
 

Plse bear with me..I'm new to Mercedes ownership-have inherited a 1985; 300cd -Problem: key on, steering col. lock frees up, all appropriate lights on, incl glow-plugs.. bat cond good ( load tests at 750CCA, holding 12.6v) will not crank. No solenoid "click".almost feels like there should be one more detent on ign switch, or that the key is not, for some reason, energizing the elect switch portion of the ign......any suggestions as to where to start looking will be gratefully received.
Thanks, Nev