My 1989 590D has the row of bolts around the swing ring of which there are 36 of them. There are 6 Bolts broken off and fallen out in this order, two broken, one still ok ,then 2 more broken, one still ok, then 2 broken. Would anyone have any ideas why they are broken off. All the others are tight. Should I replace them or just run it and keep an eye on the others for any loosness. I have made a preliminary attempt to drill and easy out but soon gave up as it is a tough time getting centered and to drill upside down in that narrow area. Thanks, Cat 236