Every once in a while, the van (90 syncro westy w/ recent Tiico I4
conversion) won't start.  This problem occurred BEFORE the (professionally
done) engine conversion.  Turn the key, and nothing, just a click.  Jump
starting the van works, either from another vehicle or from the auxiliary
battery.  Not sure how to suss out if it's in the ignition switch, the
solenoid, or the starter motor itself?  Or any other thoughts?  This is not
a constant problem, and sometimes turning the key off and on a few times
gets it starting.  It starts right up once the right contact is made.  (But
where is the contact not being made/and is it merely a question of not
quite enough juice from the main battery to override whatever electrical
gremlin is in there? )

Thanks for any and all replies.

John
SLC
90 syncro westy, Tiico powered