I did a bunch of 'Googling' and found that your exact foot control is likely to be pricey, $30-ish, with shipping and all. The manual is available in lots of places for 8 to 10 bucks. It seems that would be a bit too much to spend on a two dollar machine that may or may not work.
Now for the good news. Your machine seems to have been made on the mid 70's in Japan, and they made lots of them for many companies. Many of them used the same foot control. If you find a foot control that plugs in to the machine, it's a 90% chance that it with work perfectly with your machine regardless of brand. Keep your eyes open every time you spot a box of random cords at a garage sale, look for a peddle in there.