Replacing Anodes, and some were brass square head. I rounded one off and have tried everything I have to get it unfrozen, PB Blaster and WD40 with wrenches for square heads, vice grips and finally a pipe wrench. Been at it 2 weeks spraying with PB Blaster every time I go by it. Limited space to get at it. Any suggestions before I pull the cooler and drill and tap it out? Trying to avoid that mess. This is in the transmission cooler and I have another one back on the heat exchanger.