Heat Pumps and Electric Heating - Newbie seeking help...outside fan not turning on

I have an older heat pump, about ten years old. About 6-8 months ago a repairman was called because of trouble with the unit coming on. He replaced a contactor and all was good. Now I am having more problems out of my unit. I noticed that the unit started making a loud humming noise first. Then I noticed it wasn't getting as cool as the thermostat was set for. I walked outside to check the unit and found that the unit was humming but the fan blade was not turning. Periodically it would make an attempt to turn but then would stop. I tried to assist it in turning and it would begin to turn slowly, but not at full speed. As the blade made its attempt at turning I noticed that a lot of heat was coming up to the top cover. Any ideas on what this could be???? Contactor? Fan Motor? Capacitor? Anything to try?? Thanks for the help.

Classic capacitor.

If you can't DIY it call for service. In either case turn ot off before real damage occurs.

Thanks for the reply. I made a quick visual check of the cap to see if there was any bulging or leaking as some have stated but did not observe anything out of the ordinary. Will have to try to check it with a meter. Any certain type of meter?? What reading am I looking for??? Guess I would rather the cap go out than the condenser fan motor

This is from an appliance site.

But this is still how to test a cap.

Capacitor Test (http://www.applianceaid.com/micro4.html)