Seat belt mechanism on BMW 520i

Hello everybody,
I have a little problem with my seat belts on my BMW 1990 520i. I was chopping down some trees in my garden and I loaded up my car ready for the
tip. I noticed afterwards however that one of the rear seat belts would click into the socket. I presume that a leaf or a bit of pine cone from the trees must be jamming it. Does anyone know how to access the mechanism?
Many thanks for your time,
James Sherlock
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.