Can anyone tell me if they know of a fix or how to get into the seat belt tensioner on an S320?

The belt is all the way out, and it will not go back in. Is there a way to reset it? Or, do I need to get into it and work a fix from there? I need to know how to get into the door pillar to fix it...Thanks for your help.

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1994 S320
131K miles

1998 ML 320
126K miles

1994 Blue C220
122K miles

Im going to Grad School @ the University of Iowa
Go Hawkeyes!!!