How can you increase the break out force of bucket and arm of a Massey furgeson 1575 back hoe?

About the only way to increase the force applied is to increase the outflow of the hydraulic pump. An increase in p.s.i. should boost the force applied to the rams. You're going to have to be careful that you do not blow hoses or rams or bend steel if you raise the power too much. These systems are engineered to run on available p.s.i. and increasing it could be too much for the bucket/ram assembly.