Vortex Sound Research

My Behringer Deepmind 12 has this problem where the portamento value changes on it's own. Whatever value I have the portamento wheel to, the numbers are constantly changing. Most of the time I want the value to be 0 but the lowest value possible on my wheel is 25 so there's no way for me to keep the value at 0. This is especially annoying when I pull up a default patch and the synth thinks the wheel is being moved and will automatically change the value to someone near the wheel which means it's currently impossible for the value to stay at 0. Does anyone know why this is and how I could fix it? I would honestly be fine just disabling the wheel altogether if there's a way to do that.