Problems with the right Z axis
I've had this happen before on various Prusa i3 style printers, especially with my homemade tight self printed POM linear bearings for the Z linear shaft. The problem is that the right side Z axis has some sort of friction caused by a skew frame, probably caused by the incident you had earlier.
You need to check whether the X axis carriage goes up and down smoothly. Unscrew the lead screw couplers or the trapezoid nuts and check the movement. If it catches friction, try solve where it comes from. The friction is causing the stepper to skip steps and causes the unsynchronized up/down movement. Please check if the frame or the rods have not bent, the distance between the linear guide rails needs to be the same over the complete height.