I have a husqvarna self-propelled mower. The drive shaft will not turn when the drive is disengaged. I can turn the gear with channellocks but it turns hard. It runs merrily when it is engaged. It seems to meet resistance after turning it 15 to 30 gegrees but I can force it past that point and I see the clutch lever move. With the clutch lever as far as it can go( disengaged) it still won't turn.