I think those have thread locker from the factory. Serious stuff. I've had problems taking the rear hardware apart for the same reason. I wouldn't worry about it unless you need to change the coupler or it is loose. To remove the flex shaft loosen the two nuts from one another. If the shaft doesn't want to come out when you pull it, push it in a little. This expands the gripping mechanism and releases the tip of the flex shaft and allows you to move it. As for the grease, if you are just running for fun you can probably get away with what you have. If you start using a GPS and are trying to get that extra 1 mile/hr you will want to play around. Just a thin coating is necessary either way, don't pack it.