Hey george,

you're on the right path with applying voltage to the clutch and seeing if it engages.
You can also just take the belt off, and spin the compressor by hand and see if they're any really tough spots. or obvious signs of resistance. Most of the compressores I see go out, can not beturned at all by hand.
As far as repair, sounds like you've been down this road before. If the compressor shells, you gotta ditch all the rubber lines and ex. valve too -but you already know that.
You said you added "a can" of freon? If you were low then you have a leak, and if freon is leaking the oil is leaking. Too many times people spring a leak and think they can just "top it off" once in a while. Was there any oil in that can of freon? The compressor needs that oil badly. Just a thought.