SOLVED! Strida MK1 ball joint steering repair

I came across this wonderfull stuff, Protoplast. It is a plastic grain which melts at 62° celsius and becomes tough as nylon at room temperature. Even a thread of it is as thick and as strong as a fishingline. It sticks to most other plastics, but not to metals. With pigments you can make it any color you want.
As long as you’re not taking your Strida for a ride in Death Valley, you should be OK.
I tried it out, it’s not the prettiest, but it works and it’s solid.