PerformanceKit Installation Issue D420

Hi

I have recently purchased a Performance Kit for my D420.
Installation procedure is well detailed but I am currently stucked with the installation of the Grommet on the Axis Adapter motor. If you watch the video, installation of the grommet is quite straightforward. In my case, I can't install them as they are way too big
The external diameter of the grommet is =- 10.8 mm (for all 4 received)
The outer diameter is +- 9 mm and here I expect the diameter to be the same as the 2 holes on the Axis Adapter motor (+- 5 mm)
The inner diameter is +- 6 mm and I expect the diameter to be equal to the diameter of the cylindrical on the Axis adapter spindle (2.4 mm)

In fact, the grommet I got are the same as the one used o the plate covering the belt (removed during upgrade

I checked in the spare parts list on the shop but only find the 8 mm grommet
I have attached a picture
As they are only one grommet on the shop, I tried to find another grommet (Amazon) but didn't find any

I plan to print a part but I think I need soft material rather than Nylon or PLA

any advice

thanks