For me, inserting the spring was also not an easy task.
I managed to insert a few springs by hand, but it was not pleasant.
Then I tried to print on a 3D printer a tweezer-type device from the message above. With its help, it also turned out to insert a couple of springs, but also not very convenient.
Then I drew my little spring holder model. With which I was able to compress the spring into the window, and then push it with a screwdriver into place. It also didn't work out perfectly. The holder could be improved. But the free springs are over, and disassembling the leg is no longer a hunt.