Unpredictable layer shift on brand New Vcore

Hi ! This freshly built vcore 300 is displaying some weird, inconsistent layer shift all the way through the print. I checked the Z coupler and X/Y pulley, tensioned the belt. The printer moves fine, feel fine, extrude fine and the part is solid but its useless. I'm looking for clue to where to start the debugging process as I never had this kind of issue. The printer also run Rat OS with the exact same config file as 4 other machines which print fine. #