Mick,

I had a similar problem driving my Syncro. Fortunately, I discovered then
coming loose before they completely came apart.

After making several inquiries with knowledgeable Syncro folks, I was told
that this was a common problem if the 12 point (XZN) bolts are not torqued
properly.

I tightened them back up to spec and have not a problem since.

Ben T