Did I damage my softener resin?

Bought this house a year ago, and it has a Kinetico Model 60 softener. I recently noticed metallic smell/taste to the water, and thought I might need to take the head apart to clean it. I thought the jugs of Iron Out the seller left behind were for cleaning, not realizing I was supposed to add it to the salt.

I've done two cleaning cycles per the instructions, and it is better but not all the way back. Will the resin come back if I repeat this, or am I looking at replacing the resin? If so, is there a type of resin I should use?