Posts: 1,162
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Joined: Aug 2005
When you say 'hard to use' do you mean that they can't be pressed, or that you can press them and they feel normal, but they have no effect?
Posts: 6
Threads: 3
Joined: Jan 1970
I'm not sure if your keyboard has the same construction but I used the following method with succes in my 41CV that had a faulty 'ON' key.
The keyboard consists of little dome shaped metal springs that provide electrical contact with a pad on the PCB once you press it. And they also provide the positive tactile click that we al like so much. You don't have acces to the springs because of the moulded plastic studs you mentioned. You can however see the PCB pads on the bottom side of the PCB since they're through-hole metalized. You can even see the spring moving once you press a button if you peek through these holes. I used a needle to insert a tiny drop of contact cleaning fluid through these holes. After pressing the key a couple of times to make the fluid do it's work, the keys functioned like new again.
Don't be tempted to use the spray-can of cleaning fluid directly on the calc,since it will penetrate al places where you don't want it. Just spray some in a little cup and use a needle to put a tiny droplet into each hole on the PCB that has a faulty key behind it.