I have a 2003 Sportster 1200c. Over the last 2 weeks it has been hard to shift. I pull in the clutch and it just doesn't want to shift to the next gear. I have to use some force to shift it. Yesterday it became really hard to shift. Also, there is a knocking or rattling noise coming from the gears while I have the clutch lever pulled in. I tried to adjust the clutch cable but I'm still having the same problem. Todays my first day without riding my bike. I don't have a second bike or cage. I need to fix this fast. Any recommendations? Where should I start first?