We have recently discovered some issues with our MZA4 boards and the following steps will show what needs to be done to correct any possible problems.
This picture shows the excessive amount of copper on the side of the board that will cause short through the motor pick up spring to the power pick up part of the chassis.
Here is a picture where the excessive amount of copper was removed. The procedure was performed using X-acto knife equipped with brand new razor. The copper needs to be scratched off of the board as shown in the picture above.