I decided to leave the gamepad from the originally purchased PS2 Slim, because it is original, and indeed two - are better than one. But since he had rather serious problems, he had to repair...
• A loop for the gamepad - http://ali.pub/26j9ab
• Connector for a loop - http://ali.pub/26j9e0
• Sticks for replacement - http://ali.pub/26j93i, http://ali.pub/1zhdf4
• Desoldering pump - http://ali.pub/26j90s
• Soldering iron - http://ali.pub/1cm05a