Should I replace my case fans?

[BuildNoob]

I have a old Lian-li case (model PC-7) with 3 fans in it, I don't know anything about the fans except their 80 mm, Should I replace them with some new 80 mm fans?
( I'm new, excuse me if this is in the wrong sub-forum)

 

[leeb2013]

are they noisy, faulty, plastered with dust or broken? If not then they should be ok.

 

[BuildNoob]

Nope none of the above, just old I think.