sun roof won't open

2001 X5 sunroof will tilt but not slide all the way back. Something inside is rattling and I know it had an internal broken part. It's gotten worse and now will only slide back 3 inches. How do I disassemble to find out which part is broken?

you have to take down the entire head liner to get at the sunroof. if your up for a job like that then by all means. It's kinda easy but boring.:banghead: