Actually a thicker "tool" might help you in dissassembly.
It appears when you replaced the extended floor plate you failed to replace the spring to begin with. A longer magazine spring is required with extentions because you are making the inside of the magazine deeper(longer),
The orginal spring is still very much usable and should still function in the standard configuation.
Welcome and thanks for your video..I am sure it will help many here. My only question is: Is your mag extension a Plus 1? I added the Pierce extension on one of my mags, but it is NOT a Plus 1 so it was pretty much solid and added very little if any space for the mag spring to expand into so I have not had any problems what so ever, but, going on the theory G23 mentioned, it would make sense that a plus 1 or plus 2 extension would indeed require longer springs. Something not mentioned by the Pierce or Scherer manufacturers I do not believe. Well anyway, thanks again and again WELCOME to this great forum!!
Thank you for the tips G-23 and Yogi. They are PG-2733, So for the .40 S&W it is a Plus 1. I bought the Glock from my uncle who put the extensions on when he owned it and I don't think that it mentioned replacing the spring so he didn't. Bear in mind though that this Glock was sitting in a gun safe with the mags loaded for over a year before I bought it.
Sitting loaded will not ruin the springs in the magazine..loading and unloading will. The springs are made to be compressed, and if they are not worked, there will be no wear and tear. They do not weaken from compression nor do they weaken from being uncompressed. Use does the weakening. Otherwise, a coil spring on a car would wear out just sitting..and they do not. So I believe that the spring problem was just the fact you added more space for the spring so its tension was not enough to work all of the time properly in feeding the rounds. And you already fixed it.