Your machine probably doesn't need much more than a good cleaning to work. You can easily do the work yourself. Set aside a few hours and get to know your machine better. Take a look at the sticky on cleaning machines. Muv's videos are great.
The treadle irons can be wiped down with sewing machine oil and put a drop of oil in the joints where it moves.
New leather belts are available from Sew-Classic.com if you need one. 3/16" diameter is the most common size for domestic machines. They also carry bobbin tires. If your machine has been sitting a long time both will likely need to be replaced.
Don't be tempted to use anything but sewing machine oil or Tri-Flow in your machine. Other oils will dry up and stick things together, they're also too thick.
If your machine has been sitting a long time and doesn't want to turn, oil it and spin it over once or twice then wait. When you pass by the machine, spin it again. Eventually the new oil will penetrate and the machine will free up. It can take a few days though so be patient.
I have a PDF copy of a White Rotary manual I can send you. I don't remember where I got it, maybe ISMACS.
I'm impressed with the quality of the old Whites. It should be a good machine for you.
Rodney