ok, so my unit does not have the wiggly f and g key, but the COS key requires more force to get it to work. i had to press it several times before it would work. quite annoying because it clicks everytime i press, even though it did not actually performed the operation; the clicking sound makes you think it worked, and if you are not looking, you might get the wrong answer in the calculation.
this also occurs when doing the g-ENTER-ON test.
all other keys work fine, though.