POWER RESERVE PROBLEM SPEEDMASTER REDUCED CAL 3220

GOOD AFTERNOON, I HAVE A QUESTION ABOUT MY SPEEDMASTER REDUCED CAL 3220, THE POWER RESERVE OF MY WATCH STARTED TO LOW UP TO LAST MAX 9 HRS (WITHOUT USE), BUT FROM ONE DAY TO THE OTHER THE WATCH STARTED TO STOP AFTER 5 MIN OF USE, WHEN TRYING TO WIND IT MANUALLY OR WITH MOTION, THE WATCH REMAINED THE SAME OR WORSE, IT WAS INCREASINGLY COST TO GET IT RUNNING, IN A DESPAIR START I ACTIVATED THE CHRONOGRAPH AND TO SURPRISE THE WATCH WORKED AND EVEN WORKS FOR AROUND 30 HRS WITHOUT USE (WITH POWER RESERVE) WHICH DID NOT HAPPEN WHEN I WAS USING IT WITH THE CHRONOGRAPH OFF, AND EVEN THE LOGIC WOULD INDICATE THAT WITH THE CHRONOGRAPH ACTIVATED THE POWER RESERVE SHOULD LAST LESS, BUT ON THE CONTRARY, IT LASTS LONGER,
IT IS OBVIOUS THAT SOMETHING MUST BE WRONG, BUT WILL THEY HAVE ANY LOGICAL EXPLANATION TO THIS?
THANK YOU

Thank you