Your lucky the homebrew fix worked , I tried three times using items out of my " plastics junk box " ,and failed. Then I did buy the INFINITI genuine part , and was clear like said in a previous post how a revised part now. The difference I noticed from the original black one was - the new clear one was very much a softer kind of like rubber compound , not plasticky plastic that crumbled over time.
Problem was how much force needed to ' seat ' the grommet into the hole in brake arm , because it has like an expanded tip / groove that has to be over-inserted to catch and STAY !!!
What helps this is silicone grease on the arm OR the grommet itself , and then you really feel it pop in
Heavy pressure on the center with small curved needle nose can expedite this technique.