I use a stiff cable tie to straighten the fins less chance of causing any damage to them that way. Then maybe sand blast it clean before a nice coat of fresh paint and refit as good as new. If you do blast it clean make sure you block up any of the openings the last thing you want is any of the grit inside.
I said straighten them not attack them - plastic is a good suggestion if you don't have surgeons hands though
Get a mate who works in aircon to give you some condenser cleaner to get it shiny and new. Degrease and clean the hose. Do not sand blast the fins they are way too delicate. You can bend them with yer tongue!
Soda blasting is a good option. Cheapest bet get some kettle descaling powder from the quid shop soak it In that for half hour.
Cheaper than buying an aircon mate a pint A long as you know how long to soak it for....:Bag: :Nailbiting: :Banghead: