You don’t mention needing a Service Manual; maybe you already have that and only need a parts manual.
The 399 page Gale Service manual is available here:
https://www.manualslib.com/products/Gale-35de10-3995806.html
You have to jump thru a couple of “I am NOT a robot” hoops but I have downloaded a few things from them and it seems legit. Free and pretty good quality scans on a huge variety of stuff.
