Styrene end caps for the aluminium bed extrusions

[chasgould]

Hi Guys,
Does anyone know of a source for the plastic or styrene end caps that go over the end of the aluminium bed supprt beam extrusions? These fit over the inner bed rail, to keep it captive inside of the outer bed rail. These are the aluminium rails that allow the sofa to extend out to a double width bed, and mine just flops over because the end cap pieces are cracked and missing.
Also, does the rivit have to be removed and re-riveted to attach them, or can the cap be pried over the existing rivit. I don't know how you would re-rivit while the rail was in place, and it won't fit into the other rail after the cap is rivited on.
Thanks,
Chas