Replacement tweeter for LSi25

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I cannot be sure at this point if I have blown or am in the process of blowing the tweeter in my right channel LSi25. I noticed some "scratchy" sounds out of the speaker the other day while listening to an album I'm very familiar with but didn't have the time to investigate it. Today, I got a chance to listen to some music again and noticed that when I turner my system on, I could hear strange intermittent sounds coming out of the tweeter. After that, all seemed fine and I haven't noticed any issue. At any rate, how much would it be for me to order a replacement tweeter from Polk for this speaker? How difficult is the replacement process? Thanks for your help.
Music and Movie Rig

Samsung 40" HDTV 1080p
LSi25 Front Speakers
LSiC Center Channel
LSiFX Surrounds
Rotel RB 1080 2-Channel Amp
NAD T763 Reciever
Denon DVD 2900 Universal Player

Audiosource 10 Band Digital Equalizer
Audioquest CV-8 speaker cables
Audioquest Sub-X subwoofer cables
Audioquest King Cobra Interconnects

Monster AVS 2000 Voltage Stabilizer
Playstation 3 120GB Slim