another one here – it really is worth persevering as it's a faff to have yet another tool, especially one that isn't exactly trailside friendly. I think it's down to having the special link really clean, a tiny bit of grit can clog up the sliding action. First time I managed to split the chain tool free, after ages of struggling, with only colourful language to assist me, I was as delighted as you are with your lovely new pliers. It works best if you push the chain together, so that the paltes of the speacial link are at 90 to the rest of the chain, then pinch the plate mid point between the rivets. once you've got the knack, s'easy – honest.