Scroll down for diagnosis.  Textbooks and FSM of no value.

Symptom:  This is an intermittant starter malfunction.  Most of the time,
when the key is turned to "start" the engine cranks normally.  Sometimes,
however, there is a momentary delay before starter engagement.  During this
delay, there is no sound from the starter or solenoid. The delay can range
from a fraction of a second to several seconds, but the engine always
cranks.  Sometimes it helps when the key is switched several times.  When
the key is in the start position, the engine warning light illuminates and
the dash voltmeter dips.  The engine is an inline four, turbocharged, fwd
configuration.  What caused this odd fail to crank difficulty?  Answer
below.
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The starter motor heat shield.  The heat shield is a composite of
insulation fiber with a heavy foil relector.  When the shield deteriorated,
the foil came into contact and shorted the relay-actuated solenoid power
input terminal. When the switch goes to start, the solenoid terminal is
partially or fully grounded, depending on the corroded foil surface
condition.  The unfused solenoid power input would arc or melt a hole in
the foil, at which time enough current would feed into the solenoid to
actuate it and close the starter motor contacts.   From engine operation,
the loosened foil would move about, sometimes shorting the terminal and at
other times, not, causing a difficult-to-diagnose problem.  When the
problem was resolved, the foil was full of burned spots and holes. The
starter and terminals are not readily visible for mechanic's inspection or
attachment of multi-tester leads in this model, making the intermittant
even harder to find.