I agree with what Rodney says. (Welcome back Rodney!) It is worth doing it right but in the meantime, it's worth feeding it and helping it not deteriorate further. My bottle came from an Antique mall but I think some of the home improvement places do carry it.
My top wasn't as rough as yours but it had some of the same discoloration on it and the Howard's hid that and gave it some much needed healthy moisture.