Foggy scope, Terminal case of fogitis

The old scope on my original Excaliber has developed a case of the fogs , On my last hunt at the moment of truth , put scope up to find blurry pix , still managed to find the spot I was after..

Questions ; Could I have done any thing to prevent this ?
Can it be repaired ?
Will the "red dot' scopes preform well on a cross bow ??

Comment ; This scope owes me nothing , it,s 25 yo and has harvested a pile of venison, two turkeys and a couple of coyotes.. Don't feel the need for finer optics , most of my shots are under 25 yds..

The little I do know about scopes Dave is that for a crossbow it has to be crossbow specific . I have a crossbow here a nephew put a rifle scope on and it's no good anymore and have heard of this happening before .

TD

I'm not 100% sure but i believe the scopes fog up when the seal goes. They are filled with gas and when the seal goes its time for a new scope. The same thing happened to my 22 scope I had when I was a kid. Its like trying to look through it when you breath on it, all the time.

Check the brand name then google whatever their 1-800 number is. Most brands have a basic fee ( $30) where they will " recondition" the scope. Clean it up, new seals, etc. If they don't have that you will usually get a deal of some sort on a new one.
Trick is to stick with it until you get to talk to a real person.