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To clean the rod type, you will need to use steelwool or a greenpad. Do not use sandpaper as this may damage the sensor.
Locate the rod type sensor that will be positioned pointing at the flame burner area. It will either be able to just pull out or it will have a screw. If needed , unscrew the sensor. There is probably a thin film of carbon buildup that you will need to clean off. To do this just rub the sensor with the greenpad or steel wool with just enough pressure to scour the buildup off.
If you need additional help with this, please let me know.