What happens a lot is this: There is a little bit of play between the retaining tabs and the top or bottom (outside of the unit) so they keys actually slip off the top or bottom. The only solution that I have found to this; is that two people need to work in unison to remove the unit.
What might have to be done is that as the keys are inserted and if you don't feel them clicking into place is, for the upper - give a slight lift on the finger held portion until you feel it click but keeping lifting slightly (not too much or you'll bend the keys). For the lower portion do the same thing except push downwards slightly and keep this light pressure until the keys click. While keeping pressure applied start pulling the unit out.
I have seen a number of different keys that have just enough flex in them to cause this problem.
Hope it helps and works.
What might have to be done is that as the keys are inserted and if you don't feel them clicking into place is, for the upper - give a slight lift on the finger held portion until you feel it click but keeping lifting slightly (not too much or you'll bend the keys). For the lower portion do the same thing except push downwards slightly and keep this light pressure until the keys click. While keeping pressure applied start pulling the unit out.
I have seen a number of different keys that have just enough flex in them to cause this problem.
Hope it helps and works.
