I am back in town and put my 504 up for auction on eBay. It has the original Partridges and was just serviced by Hiwatt guru Victor Mason. I'm in the US, and although the auction isn't set up for international bidders, if you are outside the US and interested send me an email and we can probably work something out. Thanks!
More pics and better description at the eBay site: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0570546395
Thanks again!