I have no experience with repairing slipjoint knives, but I've torn a few apart and made a few from scratch. I seems to me that in order to repair that broken handle scale, you will need to have the knife apart in order to peen the pins that hold the handle on. When you take the knife apart, you open a whole new can of worms. For example, the brass liners are likely to get bent when you take the knife apart. Now you have to replace them too. One other major problem you will have if you do not take the knife apart is getting the holes drilled in the replacement handle scales in exactly the right spot. Normally, the handle would be glued to the liner and the holes in the handle are drilled thru the holes already in the liner. Hope this helps. -Phil