cam knobs 2009 outback

[jfh270]

Unable to get search feature to work correctly so if discussed before please excuse a rehash. How do you know if cam knobs are worn? Appear by picture that the bottom is flat. Mine do not appear to have much wear but mirage drive is loose. Bolts had backed out some and tighten down.

Bolts may be stripping out. I will try again and see what happens.

If bolts are backing out, what is the best fix?

Thanks
Lots of questions for 1st post.

jfh270