Just a quick update to my warning light / charging problem.

Thanks David, Joel, and Sean, for the advice.  I started to check out the
brushes and found that one of the two screws that retain the brush set was
broken off and the brush set had rotated on the other making the brushes wear
unevenly.  There were a number of other little things wrong with the
alternator so I opted to replace the whole thing with a rebuilt one.

That fixed my alternator and coolant level light problems.  I am still not
sure what to make of the oil light only coming on for an instant and then
going off (without engine being started), but am happy to have the charging
system up and running again.

Thanks,
Roger