puzzled

Small leaks can be a pain does the primary and secondary both lose air of just one chack the dash valves there common for leaking but I'm gonna say its most likely at the valve they replaced you can use soapy water in a spray bottle I like to use the bubble stuff that kids use to blow bubbles cheap and works great also check the drain valves at the air tanks might have one leaking after they drains the tanks does it bleed down with the trailer brakes set?maybe the checkvalve was not the problem

 

If it was not doing it before the valve replacement I would check the drain valves and then the valve they replaced sounds kinda fishy they replaced the valve and now its losing air always go back to the last repair and just double check it they the valve must go to brake system because you are losing air from both primary and secendary do you know what they replaced exactly?