I can’t get the teeth in the fuel line holding the knobs @ the end of my fuel filter to release. I’ve tried the tool that I bought, but can’t budge them. Is there a trick to doing this? A fuel filter is under $10, but to have it done is $80 - $100. I have the same arrangement for my Ranger, Sorento @ GMC. It’s not an Audi.
Have you tried twisting the fuel line? Yes, sometimes they are very diffilutt. You might consider just slicing the fuel line and replace that section.
I agree that you need to try twisting in combination with pulling. Over time the O-ring seal in the line hardens and the stiff rubber can make it a wrestling match; tool or not.