[C320-list] Cabin light fitting replacements?

[Graeme Clark]

our 1996 320, #303 has  circular cabin light fittings with a white plastic outer ring which is a push-fit to hold the clear lens in place. Many of these rings have cracked which means as well as being unsightly the lens falls out from time to time!

Is there a simple to sourced straight replacement anyone can recommend which won't involve any/much resizing the hole?

Thanks
Graeme