Steelhead addict:
I've had the same problem w/ several models of Amb reels.
The freespool brake is a copper plate in each end of the reel, one in the adj knob. If you've cleaned it, it will be dry. Light oil, just a drop on each plate, will get it working right again.
I dont grease anything. Mfr recommends only light oil, and just a little drop. more will only gum things up. If you have the oil that came with the reel, it's reel good. Doesnt seem to thicken w/ cold or evaporate.
Also, when you reassemble, the casting release plate needs to be clicked so the detents will match up easily. I had a new C4 5600 go bad inside of 1 month cause I didnt know what i was doing. The other thing to be careful of is the little brake buttons need to be pressed in on their pins, otherwise they will be jammed when the gear plate goes back on.
Good luck.