That might be the wheel cylinders. New means not functioning. Did you know, when you assembled the wheel cylinders, how old are they? Have they been propperly assembled, is the surface inside ok?
I ALLWAYS disassemble new wheel cylinders, clean them in straight alkohol, check the inside, rework them, clean again, regrease with brake grease blue and reassemble them. I had the experiance before that a new whell cylinder is leaking after several weeks for I did not follow the known procedure.
If it is grease or oil you will fell it between your finger tips. Than you have to take the side of the axle appart and propperly reassembel it with the correct torque values. Else you overstress the bolts and they will fail. In part 34 you find a desription of this work.
M715 since 1982

Wolf