UrQ hot start problem

[R1chT@aol.com]

Now that summer heat is here, I am experiencing a problem, which occurred
last year as well. When it is hot outside, and I have run the car long enough
for it to get hot,  my '83 UrQ will not engage the starter until the engine
has cooled for about 20 minutes.

I suspect the starter solenoid or the starter itself, possibly poor contacts
on the commutator. Of course, this always happens when I'm not quite prepared
to go poking around with a meter.  Is this a familiar problem with anyone?

TIA

-Rich 
Concord NH