I have a couple of used ones that are the same. I make an effort to soak them upright and upside down with hot water and whatever cleaner your using. It seems to get clean and work fine.
I just bought a new keg from NB and Love it! I don’t think the poppets will be an issue if you just wash them good. I also push PBW and Starsan through them, so I don’t think anything can really build up in them.
FWIW, I always leave some Star San in the keg and then charge the keg for storage, pushing the “out” poppet to discharge a little Star San through the dip tube. Then just before racking to the clean, sanitized, stored keg, I push the “out” poppet valve to discharge the balance of the Star San. That way I know my dip tube is fully sanitized. For the CO2 “in” side, I guess you can get at it from the inside of the keg or rig something to hook up and pump Star San through it.