1990 535 ia I tried to replace the O2 sensor without lowering the exaust system. Some board members seems to be able to do that, I tried for a couple of hours to remove the old one, without success (very tight setup). Is there a TRICK or is it just me being incompetent. I am a little bit concerned about lowering such an old exaust system (otherwhise still very tight, no leaks). If I have to do it, would you loosen only the bolts attaching it to the exaust magnifold then unhang it from all its rubbers? Do I need new gaskets before I begin ???? Thank you all for much appreciated help.