the belt guides are bent. usually 3/8" round stock. bend em so the belt cannot fit between them and the pulley
Most likely cause - incorrect belt due to measuring the worn and stretched one you removed, instead of going to the Sears store with the model # and serial # and getting the correct belt that way. If the new belt you got was not VERY difficult to install - and the correct belt WILL be VERY difficult to install! Then I can assure you that you do not have the right one... If you indeed do have the correct belt, then incorrect routing or other mechanical issue is the cause.
IT is normal for all Multi speed Belt drive mowers to take a moment to reach full speed in the highest gears, a worn or incorrect belt will exaggerate this and a correct new, properly installed belt will reduce it, but all will exhibit it to some degree.
You have the wrong size belt.
I have a 17.5 OHV Craftsman lawn mower, everytime i press in the clutch the belt falls off the tensioner pulley or the transmission pulley. sometimes if it doesn't fall off I look at the belt its either twisted or backwards. Also if I put it in 6th gear and let go of the clutch it takes a second for it to get up to speed, even if I give it gas. I replace the belt and the pulleys and it still has this problem. All the original belt guards are on it also. What the heck is wrong with it!?
