Try hifimanuals.com. This is a very decent amplifier and worth changing the tubes out. They come with I believe Chinese and the performance improves dramatically from openess of vocals to a much more solid bottom end. Enjoy.
techman777 is an eBay seller who has served me very well and fast in the past. I know he has Luxman manuals and he might have yours. Cost is generally $6.99 for starters and around 12 bucks if you use Buy It Now.