Made the lock ring/hole bigger and made the cover a bit beefier. 

Note:

In Cura, you may get a model error. The part will still print fine. I was able to print it 
(I used PETG at 10% infill), and it came out just fine. I used it to lock out a couple 347V switches, and the part was surprisingly sturdy/resilent for being printed at a 10% infill.