Speaker damaged, want to fix it, need service manual or some more info

Hello! So I noticed a damaged speaker on my B1 digital piano, and I would like to try to fix it myself. I've been looking for the Service Manual of the B1 piano, but can't seem to find one, and I'm not sure this one is leggit: https://www.partsisparts.net/catalog/kor... (not going to pay for it if I'm not sure its not a scam)

Can anyone help me with finding the service manual for the B1 piano, so I can safely open the keyboard without damaging anything? TIA