Vibrac, I tried both of those outfits 6 months ago when the accident happened. One responded to the negative, the other didnt respond at all.
Greg, I suspect you are right, no speedo drive, although that said, the speedo drive side is OK.
Bill, what Mg plates does your brother have?Like most metals, there are a number of different Mg alloys, some survive better than others over time. It is usually corrosion which compromises their strength or integrity & that should be visible & easily identified as a powdery accumulation on the surface. My objection to Mg alloys is the way they change size & shape over time. As an aircraft machinist I had the misfortune of having to reclaim Mg components, Alison gearbox housings & RR engine casings mostly. Clocking accurate datums was always a drag. Our friends at RR added radio active thorium to their Mg which of course made them H&S friendly as well, not!
The Mg brake plates may have moved few thou, the shoes may no longer be square or true to the drum. Try them, apply the brakes gently & if they work smoothly keep working them harder in safe circumstances until you are confident that there are no untoward reactions, shuddering, squealing, lever pulsing etc. If they are good, use them.