One more thing to consider is that the hydrolic pump breaker is popping. This is generally an automatic reset breaker. If that is the case, as said above, check fluid levels first. Also, if the temperature is very low and the pump is in an unheated space, it may be too thick for the pump. In some units this breaker eventually fails. Check with the manufacturer before taking any serious action. You may need to substitute a new, higher amp breaker to allow the pump to get going. Do NOT do this without both the hydro manufacturer and the trailer manufacturer agreeing it is ok. You don't want a fire.