I am looking for some practical advice (or maybe sympathy...)

We recently purchased a new regulator for CO2 tanks; this particular regulator has a washer and the accompanying manual says if the regulator comes with a washer, to use the washer. I have attached regulators for more years than I care to count, but this is my first with a washer....

I was doing a training session for the end users and it turned out to be more of a physical comedy show, as the washer kept falling off/out of the coupling 'thingie'. The tank is in a tricky space, but there is really nothing to hold the washer in place and the vendor's rep said using a bit of tape or other sticky material to tack it in place on the regulator side of the fitting was not OK. We ended up not having the right attachment for an accessory so used the old setup. Now we have the complete ensemble all set to go.

Does anyone have any 'tricks' or advice in how I can attach the regulator keeping the washer in place without looking like a complete klutz?

many thanks!
Margaret
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