I found it difficult to turn the bed leveling knos so have replaced them with the ones shown here. The spring retainers align the springs in the centre of the screws. I was going to use a tool made from bent wire to hook into the slots in the new knobs but did not find it necessary. STL file for the DTI holder https://www.thingiverse.com/thing:2806494 Inexpensive DTI https://goo.gl/YexD6u Knobs https://www.thingiverse.com/thing:2807363 Cup https://www.thingiverse.com/thing:1005050 Video https://youtu.be/SaFWk380fsI Cup https://www.thingiverse.com/thing:1005050 Update 17/04/18 File for larger stronger knobs added.