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Proximity Sensor not working on iPhone 3G 16GB White version. I have: removed my case cleaned screen cleaned around edge of touch screen used air to blow out speaker holes reinstalled apple 3.1.2 firmware rebooted What can I replace to get new sensors?

You can get the new replacement from ebay. They are very cheap but it will take about 3-4 weeks to receive it unless you want it from the us. Cost about 10 USD. But make sure when you are replacing it to not destroy or damage the Sensor Flex Cable Metal Holder. Hope this helps you

You don’t need to split the touch. There is one vague video on youtube which you might like to refer to. http://www.youtube.com/watch?v=7KXIOyWXu