from what i gathered from following this thread early on, there are 2 types of SVD's...ones with pressed on heads and screwed on.....most of the button issues i noticed were with the pressed on types....to tell the difference the screwed on types have two opposing indentation marks on the base of the head....IDK anything for sure but i have been wondering about this.
my SVD has a pressed on head bought from KP in Feb and everything still works fine, the button has seemed to have gone a bit softer since, still clicks tho....at first the button was tight & hard, not so now.
I don't know about the pressed head part (to be honest I don't even know what part you are talking about

), but I do know that there are (at least) two different versions of the SVD. Mainly because of the differences I've noticed in my SVD compared to the one PBusardo reviewed in Feb 2013.
Here are the changes I've noticed between my SVD and the one he reviews:
1. The button on mine is black, his is clearish white
2. He complained about how when you press the +/- button it automatically changes the Voltage/Watts up or down, but when I press mine it shows my current setting, and only if I push it a 2nd time does it change.
3. The bottom caps are different - pic below: (the one on the left is the version in my SVD - the right is a screenshot from his video)

4. The plus and minus buttons have been reversed so they are more correctly oriented (on his the minus button is on top of the screen and the positive is on the bottom).
The funny thing is that a lot of the things that were changed were things PBusardo complained about, so either Innokin watched his review and actually listened, or he may have had some input in the changes.