Be sure it has an OEM transmission belt. I believe you are referring to; when the engine is running and you depress the clutch, it is extremely hard or impossible to shift. The reason is that the belt is not fully disengaged and is applying a slight load on the transmission pulley, the belt tensioner is not fully releasing the tension on the belt, or the belt is the incorrect type and size. You can try shifting while pressing the pedal down far enough to release the belt tension but not engaging the brake...shift while rolling if you get my drift. I would check the belt condition and check the condition and tension on the belt with the parking brake engaged. If all is well, I would replace the belt with an OEM Poulan belt. It is a common issue with those types of transmissions as they get old. Check the tensioner pulley on the release arm to ensure the bearing is good. back the brake adjustment of so the brake doesn't engage until the pedal is fully depressed. In summary, remove the mower deck, remove the transmission belt, check tensioner pulley by sinning it with your hand to ensure the bearing is okay, replace the belt from a local Husqvarna dealer and not an Amazon "Special" no-name belt and hopefully it will work correctly. Again, try shifting while the tractor is still rolling, and the pedal is depressed briefly. Let us know how you make out okay. The belt part number is
AYP 532419271and can be ordered here. Keep in mind, that is an old tractor with a flathead Briggs and it may simply be a worn transmission.
