Fuel line retainer and dampener

[tod.branko_imp]

Hello friends, been a little while. The temps here soared to high 40s (°C) so I used the time to do some body work. I'll post a teaser, but it's far from done. Anyways, I need some help, the body shop guys lost the retainer and the dampener while doing the tank job, still don't understand how because I applied masking tape before taking it to the shop. I managed to source out a retainer here locally, but couldn't find a dampener, and it's been on backorder for over a month.
I'll entertain any ideas of how to make sure the retainer doesn't fall out when I reattach the fuel line to the pump. Thanks!!

Pic of the new look

'14 CB1100 STD 5 speed