Welcome to AAPK!! I also recommend taking the knife completely apart. I have tried to replace handles without taking the knife apart, and I had a rough time of it. It can be done by experienced mechanics, but without the tools and experience it is just too hard to do. At least, it was for me.
If you are hesitant to do that on such a sentimental knife, you might want to buy a couple of cheap knives off of eBay and try them first. It is a lot of fun!
Either way, you will probably want to replace all of those pins. When that center pin comes out, the springs will as well. Be sure to mark them so they go back in the same place, and the same orientation. Getting one flipped around backward can ruin your day!
Then again, be willing to think outside the box and do things that others do not, if you want.
I haven't been able to work on knives in a couple of months, but it really can be a lot of fun. I hope that this project is for you, too!
Jesus is life.
Everything else is just a hobby.