Check your wheels
Check that your wheels are inflated to the right pressure. This will be noted on the wheel.
Service your trailer
Trailers should be serviced every 12 months. You should also wash your trailer down after carrying any acidic or alkaline materials, including grass clippings and fertilizers, and not leave refuse in the trailer for extended periods. All of this will extend its life.
Jockey wheels are not designed to support heavy loads
They should only be used to move the trailer when it is empty.