http://www.quiltingboard.com/vintage...ml#post4647584
On the brown Kenmore with the flat tensioner, the above post might be helpful as far as threading. It looks exactly the same as the tensioner on the old White Rotary machines. Not hard to do, just a little different if you are used to a Singer.
The same kind of happened to me with the White FR machines...not really that interested, but then I ended up with 3 of them all in a row!
Have fun with them.