You should service your winches at least once during the preseason. However, twice a season is best if your boat lives in salt water. If you race your boat hard, you may want to maintain your winches before every regatta. Keep your winches clean and operating smoothly by flushing frequently with fresh water. Check pawls and springs, bearings, gears, and spindles for signs of wear and corrosion.
For more details, consult the maintenance manual.