The front of the compressor is turning, so I guess the clutch is engaging. It is also blowing cold. What you say about it losing lubricating oil and causing damage makes sense. Can any A.C. shop replace the oil? Is it a simple enough DIY that someone like me without any A.C. experience can handle?

Question answered
 

Techguy512's post came at the same time as mine, and answers my question.
Thank you.

If you want to fix it to last take everything apart, flush it all out and replace the bad parts. Put correct amount of oil in it, vacuum for as long as you have time, charge it and go.

I know the re-build is beyond the scope of my knowledge and ability.

How much should I expect to pay to have this done?

Is there anything in particular I should mention to the mechanic to avoid being taken for a ride and having him do more than is needed?

I guess this is something I should schedule ASAP.

My guess is $600 to $700
 

If you go with a new compressor and have the shop put it in, and vacuum it down and install refirgerant. Go with R12 if you can. It is what was originally specified for your AC system. You will also have to replace the dryer. But if you can not seal the system again because of the current leak then all the work is for nothing. It doesn't make sense to me that it would be leaking oil from the dryer and still blow cold because it would also be leaking refrigerant.