[yash101]

What COTS basically says is that you may not tamper with any off-the-shelf parts or it will become a fabricated part. This is typically used for the electronics because they don't want you to be messing with your cRIO or other robot parts!
I don't think COTS is preventing you from doing this. However, the inspectors have the ability to deem your part as dangerous if it holds back many pounds of force and can make you disable or remove that part, so be careful!

And, how the heck did you get the robot to weigh about 65 pounds? Do you just drive around and push the balls around? I think our drivetrain weighs 20-30 pounds by itself. With the electronics, we are already looking at another 10-20 pounds, making it 40-50 pounds right there. Then, you have your mechanisms. Typically, that will take up the rest of the weight!