Well it sounds to me like the thing that changed was the environment. Ice, cold, wet... If you have a garage you might try letting site in there for a while and warm up, Then open the doors for ventilation, start it up and see it the problem is solved . Stranger things have happened.
Also check the linkage from the hand clutch well below the tensioner. That has gone on mine and it was like a clutch slipping on a car.