Is the oil pump inside or underneath the small plastic motor-drive sprocket on the right, circled in red?
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There may be a discharge port pointing upward in the center of the shaft. There may also be an entry port under the sprocket, pointing downward into the oil tank.

From what I've read on various sites it is very common for the pump to stop working, but I haven't found any reports of fixing the pump, or even finding it. You test the pump in the usual way for chainsaws: run the saw briefly with the chain bar pointed at a sheet of white paper, and expect to see it instantly develop an oil stain.