Metal Mouth Message Board

Hello all,
I'm getting my braces fitted next week, so want to step up my game on flossing etc.
I have a waterflosser I bought several years ago but didn't use much. It's just been sitting in my cupboard for a long time. What would be the best way to clean this up and make it usable again? Any tips on sterilisation etc?
Thanks!

https://www.waterpik.com/oral-health/bl ... r-vinegar/ is from the manufacturer and seems reasonable. I have run white vinegar through mine as i am paranoid about bacteria growing in the internal parts of the machine.