Cleaning Palm Treo buttons

I've had some problems with Palm Treo buttons -- i.e., keypad keys. I guess they get dirty down inside, and need cleaning. The symptom is that I have to press the key very hard to get it to work. That makes typing difficult, of course.

I bought some contact cleaner --



that seems to work. I removed the Treo battery, sprayed the cleaner on the keypad and from the back, and let it drip out. Then it dried for about eight hours. The buttons work fine now.