Hello Sableco,
The top fitting which screws on the bushing may have come loose or the entire bushing and fitting assembly are turning.
This bushing is critical. It holds the vertical timing gear in place that drives the oil pump. If the timing gear rises enough, the engine will keep running but the oil pump will quit running ! Your engine will fail soon afterward.
As mentiond a 10mm special bolt "pins" the bushing and keeps it down and keeps if from turning. If this is the problem, your busning is most likely damaged and worn from rotation. The special pin bolt is loose or missing. Lots of info on the subject under "verticle timing gear".
Check the fitting, the pin, the bushing and the timing gear as soon as possible. The bushing can be removed without removing the head, as long as you take the fitting off the top first.
Here is a picture with some information and part numbers.