My K750i joystick was bothering me for a long while. Even I had trouble using the phone, imagine people who borrowed it from me. I joked its a security mechanism that only I can use it.
I Googled and found this. I had never opened my K750i before but i succeeded in doing that without a T9 screwdriver quite easily. Although I was a bit afraid of damaging its case. I did not disassemble it completely, just removed the keypad board and the black plastic below it, then pulled out the joystick cap.
Spraying the solvent is the hardest part. A small dropper should be used ideally but if you are ill equipt like me, other things might work as well. I sprayed some WD-40 in a small bottle cap and used a triangular guitar pick to put in the solvent in the joystick module. When putting in the solvent I held the joystick in the opposite direction so that a bigger gap for the solvent is created.
Put the solvent on each side and move the joystick in every direction so that the solvent gets distributed properly and if this does not work try adding more solvent. It took me three tries before my joystick was good as new(maybe better than that). First I used a pencil tip to put the solvent in, next i sprayed the WD-40 on the module(I highly recommend not to do something stupid like this) and lastly my guitar pick method turned out to be highly successful.
There are a number of solvents that can be used listed there. WD-40 would not only dissolve dust or whatever that made the joystick so unresponsive but also would lubricate it. So I guess its better to use than others, and other than that it was the only thing I had handy.
All that would be required is: a screwdriver, a small phillips did the job for me, some sort of hydrocarbon solvent, something small and pointy which can be used to drop the solvent on the module, something flat and rigid like a plastic card to slide through the sides of the phone after unscrewing, I used a guitar pick for both the dropper and card. Some tissues and possibly newspaper so that spilled solvent doesn’t mess the workspace.
I highly recommend you see this to get the idea where to apply the solvent. And this to get an idea how to open the phone. It is highly unadvisable to disassemble the phone completely, open only two screws from behind to remove the front cover only.
And if you destroy your phone in the process, don’t come crying to me, I am wont be responsible. You should not trust a bloggers anyways.