Manuals are oh so helpful sometimes
I'd suggest you rock on down to your local TSC and at least pick up the I&T manual for the Farmall letter series tractors. It's better than nothing at least.
The filter screen should be behind a plate that's held on the Touch Control unit with four bolts. Either drain the fluid or be prepared for a hydraulic oil bath.
Hydraulic fluid will normally be very hot to the touch after a tractor has been running for a while. Ever been sprayed before? Let me tell you it's not fun. Hot, high-pressure oil... Good thing it was an M... If it had been the Maxxum, I probably wouldn't be able to reproduce...