Cassette players

Hi everyone. So basically, my dad has an old cassette player (Philips n2412) that we're trying to fix so that I can have it as a christmas present. The thing is, we have to replace the small belt for the rewind button to work, but I can't find a GOOD tutorial on youtube that explains how to do it, especially for Philips cassette players. So, does anybody know how to do it? Or does anybody know some good tutorials?