I really can’t understand how this would not come off using either water pump pliers or a mole wrench. It just seems that the OP is not able to use the tools properly. Nothing wrong with that, just how it is. Perhaps he should consider getting someone in. As for the mechanical engineer he got in, well, my mates son has a masters degree in mechanical engineering. My mate had to show him how to change a wheel using a jack and wheel brace.