There is approx. 1/4" space from the nut at the top of my strut to the mount. Is this supposed to be tightened down? Strut shaft can spin. How could you tell if the mount (bearing) is bad? Both sides have the same gap. This is the first time its been looked at in 18 years.

 

It's not really a gap. The nut on the strut bottoms on the bearing and the shield has a gap because it doesn't reach the flanges on the nut. The space should only be about a 16th of an inch, but I would tighten them just for good measure. To chech the bearing jack up the car. Grab the strut and shake it. If it moves around or you can feel slack replace it. You may have to remove the shield from the strut shaft to check it.