chains are cheap enough, just replace it. I have a PC69 and it supposedly has a nickel coat on there to prevent rust, I still get some at the rivets but i suppose it does help. What are you using as a lube? I use tri flow and in really wet winter stuff i use pedros syn lube. I had some rust with ice wax and i soaked it in wd40 and simple green and it helped it, but since i used oil theres been none.