Hi everyone. Did some searches and found this 1/4" socket that has an OD 17.1 which should fit based on the measurement done in post #21. Link on Amazon showing the OD, sizes.
Or you can buy directly from company and it's free shipping within USA. Only $12
I have not used this but looking to buy one as well.
Or you can buy directly from company and it's free shipping within USA. Only $12
1/4 Sq. Dr. Socket 13mm 6 point Length 50mm Z-series
Metric, ¼” drive, 6 Point, Deep, Chrome Hand Sockets. A six-point socket is designed to contact the head of a fastener well away from the corners so contact is made on the thickest part of the fastener. the edges of a socket are angled back a few degrees to allow the socket to slide easily over...
kokenusa.com
I have not used this but looking to buy one as well.