1981 cub cadet 1225 38 inch cut manual

[Rbusques]

I have 1981 cub cadet 12 hp 38 inch cut worked great for two months after purchasing but now it don’t want to drive forward it will but barley it seems to drive better in reverse I have notice to got to rock back and forth to change gear to 1-5 or put in reverse the belts are tight and seemed to be lined up I did notice that outside of one belt is peeling off but still looked to be fine when you pressed clutch and put in gear it will pull forward but slow and starts jerking like something is slipping please help and thanks for any suggestions