A 1/4" is slightly larger than 6mm. I had one of the studs strip like that and I just used JB Weld to fasten it back in. That was about 500 miles ago and it is still holding. If it ever does pull loose you can still tap it out to a larger size. Good luck! There is always something with these kits!
If it can't be broken I'll find a way!
I'm not lost, I'm exploring!