I have a number of Enduras going back to the time of the First Gulf War. One knife is a bit difficult to open. For want of a better description, there are no screws to tighten or loosen. The pivot pin is pinned like the other pins. Is there a way of taking out the pined pivot, lubricating and reassembling. i don't think it is possible. I have tried cleaning with vinegar, running under hot water and opening and closing after doing lubrication without being able to open it up. Thank you in advance for your suggestions.