I warrantied some Knipex pliers late last year. I didn't think I was abusing them but I was gripping something with significant pressure and the needle nose ends splayed out. I looked on the Knipex website, emailed the local rep, described the issue and sent a picture. I got confirmation of warranty before I sent them for replacement. I paid shipping to a neighboring town and got a new pair back a few weeks later.
Find your rep, email them, and see what they can do for you. I am the original owner, but I wasn't asked for proof of purchase, just the model number.