Brakes

Year model? There are a couple of methods. You can hook a hose to it and vacuum the wheel cylinders, or you can manually bleed the brakes using the coupler or the safety cabling. Or you can use a bleeder ball and pressure bleed them. Manually just be sure to press in the master cylinder and hold, release the cylinder bleed and tighten before you release the coupler. Repeat process till the fluid has no air in the lines. BCB

Must have a leak in the line end fittings somewhere that is letting air get in, and the coupler could be leaking, though doubtful.

You can use a small transfer or vacuum pump and connect a small hose to the bleeder on the wheel cylinder. Loosen the cylinder and pull the fluid through it. You can also build your own pump bleeder from a pesticide tank, that pumps. Connect the hose to the top of the master cylinder fill and put pressure on the lines by using the spray handle. Then you can bleed the wheel cylinders, and apply more pump pressure as needed till you bleed them out. This is a pretty simple process, and you capture the fluid in a small bottle. Watching for air bubbles as it bleeds. No more bubbles and you should be good to go again. Bleed each cylinder. BCB

You should be able to gravity bleed the calipers. I am an automotive technician and this will work. Just open up the resevoir on the tongue and make sure it is full of fluid, then go to your calipers one at a time and open the bleeder screw and just let it sit there until fluid starts coming out and close the screw. Repeat this step on the other side making sure you are still full of fluid. After that as long as everything is working properly after a few repeated stops of the trailer while being towed should work just fine.

DOT 3

Yes it should relieve master cylinder pressure and yours may be weak.

I have one that I bought for my trailer and then I ended up buying a whole new A60 actuator kit. Mine is for disc brakes. Will sell for $30.00 shipping which should be $5.00 usps. call if interested. 814-279-2306

Since the rotors are molded onto the hub assembly we doubt seriously you will find those at any automotive store. Your best avenue would be search for an old axle from a marine dealership or service center in your area and find a salvage item for a fast turn.