Before you spend the time and money for a new antenna try this: get a new coax cable and connect it to the antenna connection on the roof and run it through a window or door directly to your tv. If the reception improves it is either the existing coax cable, coax connector, or any other component in between. If the reception is weak then connect the new coax to the antenna booster (amplifier).
After 10 years being in the sun and rain, etc. it is possible that the cable is the problem. Sometimes there is oxidation built up on the connector itself and you could clean it with a product like Deoxit.