Clive here from Perth in Western Australia. I have a 15" Auto Planer purchased in Perth in 1994 (we call it a thicknesser), it has no brand name but carries a sticker advising it was manufactured in Taiwan.
A search of the web reveals that in the US it is sold as a "Planer SA 380 E. Further searching for the name of the retailer and for suppliers of spare parts has been unsuccessful.
the sprocket and chain would be available at most any mechanical gear supply house here in the US......
perhaps you have one available to you down there..
the washer and hex from anyplace that sells nuts and bolts...
Sometimes listed as power transmission supply stores. Drive belts, drive chain, bearings, pulleys, sprockets, etc. I think I have the same planer labeled as a King Canada. It was also sold as a Delta, Jet, and others. The real manufacturer is in Taiwan.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.