I can't imagine the screw would have sheared off deep in the hole - normally they break right at the place the cover meets the threaded portion.

If it turns out that the piece is broken way down in there - I could centerdrill a 6mm bolt to provide you with a guide for drilling the broken piece and using a screw extractor.

The helicoil kits work great - they really are pretty easy to use.

I got this kit.  For the price if I get one use out of the tools, great.  WE have Amazon Prime so it will get here tomorrow before the other parts.  Postal Service in Houston is a cluster f*ck (exact words of our delivery lady).

https://www.amazon.com/Rocaris-Thread-Repair-Compatible-Repairing/dp/B07F15WF...

There are different lengths of inserts, I think the one in the link is too short for this job. I'm not in to imperial dimensions.  So in metric, 10mm long insert seems more suitable to me.

The drill size for helicol m6 is 6mm. So I would immediately go to that size, because you can then use the hole in the lid to drill straight.

No mulipal small drils nessery.Because you have already pulled the thread out of the hole and it is therefore already 6mm.

I would ask someone to check whether you are drilling straight. You can only see one direction when you are drilling.

The dowel holes require longer bolts.  Each bolt should stick out from the cover 11mm before you start to engage the threads.  Here you see the three bolts along the upper side of the cover.  They all stick out 11mm.

The bolts that go in the dowel holes should be 45mm long.  Check your bolt.  Is it 45mm?

I measured the threaded portion of the hole to see how deep they drill it.  That portion of the hole is 19mm deep, so there still remains another 7mm available for threads.

Taps come in sets, with #1 (taper), #2 (plug), and #3 (bottom).  Note how the tip of each tap gets more blunt.

If you procure a #3 bottoming tap, you can cut more threads until the tip of the tap bottoms in the hole.  That should provide about 3mm more threads.  Then, if you blunt the end of the tap taking care not to cob up the thread cutting edges, you can run that in about three more turns to gain another 3mm of good threads.  Total new threads 6.  That will give you one-diameter of additional threads.  Then use a 50mm bolt.  You must verify that the bolt doesn't bottom out before it tightens down on the cover.  If the bolt bottoms, you may have to trim the bolt slightly, or possibly install a washer under the head of the bolt.

The inserts require a bit more skill and tooling.  If you mess up with an insert, it's time for a new engine case.  Try to restore with a tap and slightly longer bolt.  If that doesn't work, you can always go for the insert.  If you have to resort to an insert, practice on scrap material first.  Make sure you understand the tang and how to snap it off.  Make sure you understand how the insert locks in place once it is installed correctly.  Don't mess around with free-hand drilling.  Use a drill press to make a proper guide to keep the bit exactly perpendicular to the case.  Get it crooked, buy a case.

Well Hallelujah!!  You solved my problem Mike!!  Again!!

The bolt that I had in there was about 41mm.  Too short.  I'm not sure how I thought it was grabbing in the threads.

I went to the #17 hole (lower back near the sprocket) and there was the 45mm in there.  (I measured 45.9mm, call it 46mm.)  I tried it in the questionable dowel hole and it's threaded in there nicely and the bolt goes flush to the cover.  No stripped thread, no extra broken bolt in the hole!  YAY!!

Now I need the correct #17 length bolt which is coming in the mail.  The 41mm is too short for that hole.  I want to see this #17 bolt.  It needs to be like 45-46mm, but it's somehow a different length than a #16 (of which there are 4 per the parts diagram).  I remember having 4 of them, but somehow mixed around incorrectly.  And I was missing the #17 and moved bolts between holes thinking I had it right (obviously not).  I think the the prior owner mixed up a bolt with the sprocket cover and then I just followed his mistake.

Yay!  No drilling, tapping, helicoil needed!!

Thanks again, Mike!  You have a gift (or curse) of identifying my stupid mistakes (If I was Paul, I'd make this stupid mistake!)!  I am forever grateful for ALL YOUR HELP!!