The answer to 'tough stains on pressure washer' is that there are a few common causes, including built-up grime, mildew, or oil/grease stains. Symptoms may include streaks, discoloration, or the pressure washer not effectively removing the stains. Solutions can include using the right cleaning solutions, adjusting the pressure, or scrubbing with a brush.
If the stains are stubborn or you're unsure of the best approach, it's generally best to call in a professional cleaning technician. They have the expertise and specialized equipment to safely and effectively remove even the toughest stains without damaging your pressure washer or the surrounding area.