Do you have any pets? Most of the time, it is pet hair inside the foot control. I have taken mine apart and found a lot of carpet lint..(had new carpet put in) didn't even see the fuzz....until I vacuumed the first time. My controller was the white plastic one, not the metal one. I suspect you can open this one without any trouble. Make sure you take a picture of the in side, in case there are any screws or springs inside, you will want to know where they go back in.
My white one had a spring I needed to pay attention to....but put it back together, still working great. This one is at least $100 to replace. Ridiculous. Good luck and I hope you are able to get inside and clean without any issues.