Thanks for the update. I saw the pics on the Amazon review page and the parts look like what I would expect the innards to look like. I wonder how it came apart and I'm tempted to disassemble the 2nd one that I have ... well maybe not just yet because I don't want to ruin the spare. I'm hoping that I'll get reasonable service out of these.
So I made a short video of me inflating both schraeder and presta valves. A bit of air leaked from the presta when I attached the chuck, but that's normal for me with most chucks.