This probably sounds silly, but have you ever warmed up your strings after it's been outside in the cold? By the time I get to the gym, my racquet is usually half frozen, including the strings., which seems as stiff as my racquet. I warmed the string bed with a hair dryer when i got home today, and noticed a huge improvement in repulsion afterwards. (I bounced a bird up and down, which isn't exactly scientific, but I do think there is a difference.) I heard some talk awhile back about steaming your birds before playing... so does anyone steam/heat their strings before playing?