Jinbei TR-A8 digital flasher problem, one lamp can flash, the other lamp can't. What happened?

I also run a photo studio and have encountered the same problem. At that time, a light bulb was changed, and then there was a flash and no flash. I called the equipment vendor and she told me it was the speed of light. Just adjust the knob behind the non-flash to synchronize the light with the camera. I did, and finally the flash was adjusted. Of course, this is only possible if you are assured that you are not another problem.