Running gear is often overlooked and BCB suggests replacing springs on a regular basis. If they are 10 years old with mileage you probably need more than just lubricating and tightening. The trailer sits, tightens and rusts for weeks on end where things wear together. When you hitch it up and roll it to the lake after sitting 30-90 days between uses, everything wears exponentially as those stuck parts roll again. The bearings should be fine as the seals are easly watched and if they are not sealed you should see visible grease seepage. They suggest a solid brake inspection at 5 years with cautious viewing regularly in between. They also suggest std. greased bearing trailers get a service every 3 to 5 years. You can go further of course depending on care, conditions, mileage and sight inspections.
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