Turrets deal less damage these days

My turrets have lost their kill power, especially smokey and shaft, it has been going on for the last few days. It takes many, many hits to kill even a low ranking tank. Why is this happening?

How do I restore the power to my turrets. They have extremely low kill power,  It takes many, many hits to destroy an enemy tank....even low ranking tanks.  This has been going on for the last several days.  Can you check it out please?

Thanks,

ouch-ouch