John Deere GX335 deck height adjuster doesnt work

The knob turns freely but doesnt adjust. The knob is not broken, its not the style on youtube where the plastic breaks. I can turn the knob but the adjuster underneath does not turn. I can turn the adjuster underneath by hand. Not sure even how to get to it to repair it when i do find the cause, there are a lot of pulleys and such in the way. Any help is appreciated.