Yeah, what's the deal with this one. Mine is hard to press too. I recovered a M-185 from Robins for a fella down in Florida and his brakes were sweet and the truck would stop on a dime. I mean it. Some of the best and easiest brakes to work with I've ever seen. But my M35A3 is stiff on the pedal, and it would be hard for my wife to drive it under the circumstances, so if you find the solution, please print it here.
What makes it worse is when trailering. I about locked up my brakes on the M1061E1 trailer the first time I drove it, trying to "feel it". Felt it alright. Never happened again, and like always, you just got to get used to things, and every vehicle drives differently, so I probably wouldn't do it again unless "Emergency Stop" is needed to avoid a crash.
I love my M35A3!! Want to make it better. Please post your solution if you have one.