If encountered mic problem on nokia 1280, you may first check the microphone module, or then try to install a new replacement spare on it. Ensure also that mic's terminal contact pads is absolutely cleaned for a strong bond of connection between the microphone's terminal through to PCB's contact pads.
Nokia 1280 MIC, Mouthpiece Microphone Solution
The highlighted layout of components shown above holds the microphone circuit, if one these said components damaged or faulty and or the connection line paths is cut-off this will result to mic problem issues on Nokia 1280. You may need to trace each corresponding line paths and connected components as shown on the solution above. for it is only the way to solved the Nokia 1289 MIC problem.