If the tube's blackened towards the ends, then it needs replacing.
If it looks OK, then the starter might need replacing (if it has one). If it still flickers after replacing both of those, then it's probably the ballast that's at fault (which will probably require replacing the whole fixture).
Try swapping the starter and tube (one at a time) with ones from a working fixture, if available.
Replace the starter if replacing the tube (they're cheap). Make sure the replacement tube's power rating doesn't exceed the rating of the fixture and that the starter is rated at least the same power as the tube. Consider replacing with a LED tube.
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Happosai _,,,,_(O ; o)_,,,, Mon 22 Mar 2021, 21:15,
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