For the first time since 2004 with numerous similar Apple laptop chargers, one of the fold-out cable retaining clips failed. They pivot on a tiny plastic nub on each side & one somehow broke off & would fall out if I tried to fold it out.
All fixed now.
First I drilled a tiny 1mm hole in the body & aligned the clip before drilling into it as well. Next I increased the holes to 3mm and eased a red-hot piece of thick wire into the holes. When it was cool enough I cut the wire as close as possible to the charger body and ground it back with 60-grit emery paper on a power sander until no sharp edges protruded.
I then used a bit of 180-grit emery paper to smooth the finish as much as possible.