Vacuum Robot's left wheel is not moving.

I’ve a proscenic vacuum robot model Suzuka. Last few days, the left wheel if not moving. I’ve tested it by connecting the left wheel to the right side wheel connector and it is working, therefore I’m sure both left and right wheels are working.

However when connect to the left connector, both wheels not moving.

I would like to know how do I test and fix the power supply of the left connector?

Thx.