Has anyone ever had to replace the rear sight blade on a MK III (I'm sure the Mk I & II are the same)? What a PITA. You have to hold the spring back while maneuvering the blade into the notch and slot. Finally, after going from Plan A, to B, to C, to whatever, I hit on the perfect tool. I used a dental pick (the kind that they use to scrap the tartar when cleaning) to hold the spring. If there is a better way I would like to hear it, but this does work great.