Sheared Bolt - Timing Chain Tensioner. Now what?

So, I just finished getting everything back together after a head gasket replacement. Took my time, worked very methodically, but something felt off when I was tightening the nut on the bottom of the timing chain tensioner - it started spinning and I thought I might have stripped the bolt. (I was using a torque wrench and the top one went on just fine, so I'm not sure what happened.)

I figured I'd wait and see after finishing the job. Sure enough, start it up and it's dripping oil from the tensioner at a pretty good rate. I was thinking about putting a second nut on the end of it to tighten down, but I decided to check the existing nut and see what happened.

Well, it sheared off. See photos.

To my recollection, these threads are just part of the timing cover itself. Does anyone know whether it's possible to replace the bolts themselves, or does this require replacing the entire cover?