It is very important this time of year to check and lubricate your locks. I cannot say it enough, LUBRICATE YOUR LOCKS!!! In states that get a lot of snow, they usually put salt, or calcium chloride down on the roads to keep them clear of ice. Calcium chloride and salt get thrown into the air by vehicles. This gets sucked into brass and aluminum like a sponge, this causes seizing of the locks and deterioration of aluminum parts like thresholds, pivots, and door frames. Keep your doors clear of salt and don’t be afraid to overuse WD-40