After WD-40 and adjusting limit, it's ok now. Except sometimes it jammed in open opening going to close movement.

Is it because of internal upper bearing mounted inside bottom gate?

Is confirm the signs of internal upper roller bearings is damaged and require replacement ASAP. When the bearings worn out, it won’t able to hold the shaft firmly whenever the gate opens and close as it(shaft) will goes sideways causing it to stuck. Recommend getting stainless steel roller bearings as it’s easier to replace bearings in the near future without grinding and wielding all over again. Last I know is RM 630 for both (left and right). Make sure when you pays the guy, both roller replaced as I got customer who engage technician only grind and weld one side where else the other didn’t cause it claims the other side is fine yet charged for both side.

double post. Edited.

This post has been edited by jimmylim85: Today, 11:08 AM