Starter intermittent

[radek at istar.ca]

Hi guys.

I need your help again.  The patient is 88 90Q.  Lately, the starter has become
intermittent.  Usually it 
starts fine, but sometimes just wouldn't budge.  There is current draw (voltmeter needle
drops to about 
8V) but no reaction.  I had the starter "rebuilt" about a year ago and would expect it to
be fine.  Where 
should I look when I take it apart on the weekend?  For now, I park at high ground just in
case so I can 
push start it.
TIA

Radek
88 90Q
91 V8Q
5-sp.