Help Please!

I am trying to source end caps for the bottom rail of some existing roller blinds in our home. Previous owners of the house bought the blinds so we unfortunately don't know the brand and it's not marked on anywhere. The blinds are in great condition and are good quality, but a couple of the end caps have broken or been lost. Without them the bottom rail slides around.

Images attached. Have contacted various stores and online blind part sites, but so far this type of end cap seems elusive...

Thanks a million in advance, F