First think you need to do is to weigh the rig and get indivudual axle weights with it loaded to normal travel loads. Next is to check the axle ratings and see if an axle is overloaded.
If you tow nose high, you can put more load on the rear axle and nose low will load the front axle more.
Certain models of the trailers put the bare minimum axe under the trailer and it will reverse the camber on the wheels and bend the axle if you overload the axle.
If you wind up replacing the axles, I would go up one axle weight rating over waht you now have. I wousl also look at upping the tire load range rating.
See this is your first psot.
Glad to have you here and hope we can help to solve your problem.