I had one and hunted with it for years. I did have a problem with the piston, spring, tube etc. rusting and fouling, as I did hunt in the rain occasionally. I would disassemble, clean up with solvent and toothbrush, wipe down good, and spray down with dri-lube. I'd do this about once a season. I am looking at my letter from Winchester from 1991 abt. firing pin stating that old pin may break and become lodged in bolt face, causing gun to fire before action is locked causing "severe damage to gun and possible injury or death to shooter and bystander". They gave me a four different gunsmiths addresses that would change the pin no cost to me and a phone number for any questions, 1-800-852-5734. Don't know if this is still a good number, but try it. You need to find out if your rifle has the new firing pin. I changed mine myself by contacting them, then per their instructions, sending them my old pin with a letter stating I didn't want to send my gun off and I would do the change myself, and gave them the S.N. of my rifle. They then sent me a new firing pin, which I installed. I'm not a gunsmith, but I had the Firearms Assembly 3 book with the schematic of the Win.100, and it wasn't difficult at all. Hope this helps.
