Sure. Your guess of a cord problem is a good one. You should open up the controller in order to test it. Be careful when opening it up; many parts may come loose when taking it apart, and you'll want to see exactly where they all go. Also, if it doesn't come apart after removing all the obvious screws, then look under stickers to see if there are some hidden screws.
You'll need a continuity tester of some kind; a multimeter set to measure resistance works well for this.
Once you open up the controller, look for where the cable is attached to the circuit board. For each wire from the cable, you'll want to identify a good contact point to touch one probe of your tester with, and, while doing that, touch the other probe to each pin of the plug on the other end. It really helps to have an extra set of hands for this. You'll want to make sure that each wire makes contact with some pin on the plug. If you find a wire that doesn't make contact with any pins, then you've found a problem.
Fixing the problem may be a bit more involved, though. If you don't see any obvious damage to the cable along the length, then the most likely places for internal breaks are at the ends, either where it goes into the plug or into the controller.
If the end near the controller looks suspect, then you can try cutting back the cable covering to expose the wires. This usually requires you to deal with the cable's strain relief. Sometimes, you can just pull the cable through the strain relief; other times you'll have to cut through it. Either way, you'll want to pull in a couple inches more of the cable, open up the covering, and track down the damaged wire. A damaged wire will flex very easily at the point at which it's broken. You'll have to cut & splice it at that point.
Hopefully, that gives you something to get started with.