I have a great deal of slack in the actuator for my trailer brakes. Fluid level is good and the brakes will engage if I try to back up without the lights plugged in. It's an easy loader tandem axle, 2002 model.
How do I reduce/get rid of the slack. Jars the truck when starting from a complete stop.

Bleed the brakes

Your trailer probably has the electric solenoid that locks out the brakes when it goes in reverse. That's why it only does it with them unplugged. It's designed that way. You probably need to bleed your brakes, and check the shock absorber on the brake actuator, may be worn out and not absorbing some of the little bangs.

Sounds like the shock in the tongue is worn out. I'll bet the clunking goes away once you replace it.

Yep. It's the spring shock in the actuator.

Thanks for the response. Im going to start with bleeding the brakes and look at replacing the spring shock.