The best way to tell if the struts are failing is if they will not hold the gate up. Most of them are gas charged so there is no telltale oil leaking to indicate impending failure. Simply open the gate and watch to see if the gate falls down. If it does, especially in cold weather, the struts are failing and need to be replaced.
In my case I needed obviously replacement struts, a ratchet and a T30 torx bit socket to remove and install the struts. You will also either need someone to hold up the gate while the struts are changed out or you can do what I did, and use something to prop the gate up while you are working.
Also, you need to take notice of the orientation of the strut. In this case the body is pointed up and the rod is pointed down. The new struts go on in the same orientation.
...and here is that makeshift prop rod I talked about earlier...again a second person would be just as helpful here.
So I am first going to remove the top bolt first, though it doesn't really matter which one you start with. What does matter is making sure that the gate is supported during the removal process because again you really do not want this gate to hit you in the head.
As you can see here, the bolt is somewhat permanently attached to the strut. At least this way you don't have to worry about losing hardware.Installation in this case should start with the upper bolt, then the lower bolt. At this point, open the gate again, and make sure it stays open. Just as a side note, these are replaced in pairs to ensure proper operation and long service life.