A while ago, a friend of mine was having some problems figuring out what to do with his filter, given that his needs a replace, a quick one. So, I thought about it a while and noticed that I never actually had to do that. So, I thought I might as well try to fix his own filter as my own experiment.
It actually tuned out to be a tad easy, good for us nubs I guess.
First if all, you go to your furnaces shop and by a new cover (, and yes I don't know its name) .
Then, you gotta get a screw driver (happened to be beside my computer).
Next, you gotta take out the old cover my unscrewing the screws :p.
Then, you put on the new cover and build it on the old frame.
This actually turned out to work pretty well, I hope it works for you.
Btw, you might also want to get a new frame too. If so, I suggest you get the carbon frames.