JeryMaker

Hi, I'm using an old ultimaker 2 (2014) upgraded in 2+ end of 2016 During a long print (12h+), I realized that my print was shifting on the left. It happens at the end of the print (obviously...) and I have quickly checked the pulleys, the usual culprit. Every thing was looking fine but I have tightened all the screws to be sure. At the end, I always check if any axle have some play and to my surprise, the left y axle was moving in both direction! I have tried to tighten the grub screws again but no matter the amount of force, It still moves. Any suggestion? thx for your help! Jeremy