I have read other posts about seat belts becoming stuck in the retracted position; I have the opposite problem in my XJC, the driver’s belt is extended and won’t retract. (Although the rear ones are retracted and hard to extend).
Have tried squirting extensive WD40 into the mechanisms but to no avail so far. Do I have to pull out the rear seat squab and remove the door panel etc? Or can anyone suggest any other fixes?
Over the years I’ve fixed a number of recalcitrant belts by removing them from car for a thorough cleaning and lite lubricating…and sometimes removing foreign objects as well. Lots of ‘stuff’ finds its way into the mechanisms over the years
I don’t have any experience on removing belts from an XJ6C, though. Sorry
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Have you actually checked the unit itself, that it firmly fixed and ‘upright’? If it is out of perpendicular it will be sensed to be under acceleration - locking the belt…