Those adjusters are common to a bunch of stihl saws...all the same pt#.Lots of other options for parts. I'd be calling Stihl dealers in as wide a radius as I was willing to drive to see if anyone has stock. Plus the Ebay link I posted. Is the adjuster mechanism used in any other saw? See if you can buy a junker or post a WTB for it here. Someone will have parts.
I pulled one out of my 261 spare parts and put it on a 500i…same part.