I hope it is something simple... like maybe a judicious "touch" of something like WD-40... then (after un-plugging the KB from the electric outlet,) a few presses in rapid succession to see if it appears to be better. Other than that, sounds like that toggle switch is about to "give up the ghost." If you are good at soldering, after some careful disassembly, it isn't difficult... but if you know a reliable KB Repair Shop, taking your place in the queue of customers is usually an unwelcome wait... but the safest alternative. Good luck.