Ok, two motors. Two plugs? In series maybe?
Also, do the lights drop out? or are they wired to the roller vs the board? That puts the issue before the motors.
Try unplugging each motor one at a time. Any change in lights now?
If in series shunt the leads of each motor to together one at a time, making a tempory "lug terminal" out of a motor while its leads are shorted. If there is an issue with the shunted motor the good motor starts working now. Or, unplug and test voltage on the plug. You might need to check power with a bulb to ensure a slight load to trigger things properly too.
