If it has the front mounted pump for the loader, there is a good chance the reservoir is in the upright part of the loader frame, the loader arms attach to. If this is the case, then there should be a sight glass, approx. 3/4" across, on the left side where you climb on. Just follow your hydraulic lines going to the pump, and return side of the control valve. It will lead you to the reservoir.
I had a similar issue finding a manual. Perhaps contacting Case dealership might get you a PDF of the manual you need.
Make sure you check if the tractor frame doubles as a reservoir. It caught me off guard once.