Hi @Elliot88
Thank you for your question.
You should be able to use this Kinetic 15mm Stainless Steel Cover Plate, you may just need to widen the central hole slightly so it will fit over the spindle, as it looks like the spindle in your diagram is 5/8 of an inch, which is a tiny bit over 15mm. Check first before modifying it as it may still work.
If you need to modify it, this can be done by making some relief cuts on the outside of the central hole with a pair of aviation snips.
Once it slots into place over the spindle, you can stick it in place with some clear silicone.
Let me know what you think and if you have any further questions, please don't hesitate to ask.
Jacob
