048AV, Hopefully up for negotiation...

[stihltech]

In the shop helicoils by the dozens. Common repair so screws stay the same.
Oversize will work in a pinch or if not enough meat for the helicoils.
AND tighten the case screws. The case gasket due to loose screw is the #1 failure on this model.

Another reason for a helicoil is it gives you 1 more chance to repair the threads. Helicoil to 5mm, oversize to 6mm (sometimes) then 6 mm helicoil. I have even used the threaded bushings that Stihl used in the old 028 fuel tanks way back. As long as there is material enough to work with.
When working for loggers, you need all the chances you can get.

 

[ZeroJunk]

There's a few cobwebs on this thread... TBH I had forgotten about this saw, probably because the owner didn't want to sell it. Last time I looked at it was 2020, just checked a supplier account, and theres electronic ignition for it. I vaguely remember taking out the old bits and replacing it but I dont remember starting it. AZs I found it in a gorner of the garage I thought I'd start it now, and it started in 6 or 7 pulls. Awesome.
It does however have a fairly important issue. All the threads are gone on the starter cover screws, so here's the question... oversize and re-tap or metal specific epoxy and stick with M5 thread size? (still have to retap obvs). It's all magnesium or alloy so either will work but has anyone had this dilemma?

I normally tap them to 12-24 SAE . Allen head. Works most of the time unless there is some really high stress.
And, you don't have to reinvent the wheel to do it.

 

[Chainsaw Pete]

Joining the wires like you did by soldering might create a problem. The wires on many machines are stranded because stranded wire is more flexible than solid. Terminations are crimped and not soldered because when you solder, the liquid metal invariably flows up the strands of the wires from the termination (crimped eye or whatever). The wire is now effectively solid and vibration over time can cause it to fracture.