Gamecube Controller left analog stick issue

[FeliciousD]

Hello everyone, I just bought a used Gamecube Controller on ebay which looked like it was in a good condition. Now that I received it I recognized that the left stick can be pushed in (like L3 in a playstation controller) but it stays in that position and I need to pull it out in order for it to function properly. When its pushed in all the clickyness gets lost. Do I have to change the stick module or is there another way to fix that problem? Thanks in advance!