Restoring a Yamaha PSS-21

I found this old Yamaha keyboard at a charity sale and got it very cheap - 10 dkr or the equivalent of 2US$. It played but not very good and there was a terrible rattling sound and when it was moved I could hear that something was loose. It turned out that both speakers had become detached and one of them had even broken apart. And there was the usual dirt and glue on the keys from stickers that the previous owner had put on. I managed to get it restored - I even had succes in repairing the broken speaker which was a big surprise. The music is "All we have is tonight" which was a minor hit for Randy VanWarmer (vandvarmer?) in 1981. I play it on a collection of small Yamaha keyboards all from the PSR and PSS series.