New or used bands are available, but you have to watch for non-USGI "replicas".
Replacement does require front sight removal.
Note that there are several types of bands, since the design changed during production.
You need to be very careful to get the same type version to protect the value of the Carbine.
I'll assume you'll need a First Type Carbine barrel band assembly.
As for your Carbine, it appears to have damage to the finish, but always keep in mind that today a genuine USGI paratrooper Carbine is worth a small fortune to collectors. DO NOT remove any marks or attempt to "clean it up".
Normal cleaning with solvent is fine, but NO polishing or sanding or anything else.
The rifle is worth more to a collector in it's present condition. Any alterations or attempts to make it look better can reduce the value by many hundreds of dollars.
Here's some possible sources of original USGI bands, and some places where you can look at GI Field manuals showing the various types of band and how to change them out.
Parts: CALL them or at least email to insure you get the correct version genuine USGI part. They may have the part, but not list it.
WARNING: These may not be original USGI.
Field Manuals showing band changing:
Note the info at the top about what password and user name to use.