He needs to be looking at the Caliper for the lock ups. The rubber hoses are another thing that is overdue according to your issues. Do you not know who made the chassis. Doug might stop by. I take it your mechanic does not work on RV or he would know what chassis it has and to look at the other components also. Looking on their site it is a Roadmaster Rail Chassis. It either has a propane gen or a diesel.
http://sourcerv.com/RoadmasterR4R_FMC1109.pdf
Your coach should have the Roadmaster R4R (rail chassis). You will have one of the following rear differentials: DANA S-150, Rockwell RS15-120, Eaton 15040S, or DANA 80. Because Monaco built those chassis themselves with outsourced parts from various suppliers, the braking systems can vary. Once you know which rear differential you should be able to know which brake system you will need for the rear.
These guys will or can help you with the front brakes.
https://www.hendersonslineup.com/monaco-repair-service