I lived with a stuck dual clutch in my 660 last growing season. The only way to engage the PTO was at very low rpm with a small amount of grinding or engage prior to starting. PTO would then be turning, even with depressed clutch. Unstoppable with a 2x4. That meant spilled fertilizer, small seed etc. with broadcast spreader. 6 weeks ago, with the clutch pedal in "pointing to the sky" setting, I blocked it down with a piece of 4x4. Started it today and the problem was gone. I can live with blocking it when not in use. Might I get a shot at the clutch with brake cleaner through the starter port or the underside cotter pin plate under the assumption the clutch has oil contamination causing it to stick together? Clutch seems to have life left and pedal is adjusted for free play and height as per manual.