Hi, my cabinet is a different style than yours but I do know about those 'buttons' on the lid top on my machine. One button fell out when I had the lid opened so I examined it. Mine are wood buttons and it seems as if they are shrunk due to drying out. I haven't replaced the one that fell out yet but I plan on just using wood glue some time.
Regarding the irons, I'll take a look at mine when I do down there today and see what mine are like.
BTW: I am just not able to bond with this machine. I've cleaned and oiled the machine and treadle and I still am just not liking it. It has nothing to do with the hand wheel going away from me; I am used to that due to my old White. I thought I would love it but I MUCH prefer the Singers, Davis NVF, WW8, and Willcox and Gibb treadles. Does anyone else feel the same about their WW9?