Baby swing slowing down ??

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Okay so we have this swing ...

Now my sone is 14 pound-ish so still under the maximum weight limit for this swing . It is plugged in so no batteries to die. But now it seems to be slowing down and not swing as quickly as it used to? Any one else have a swing like his or this swing and have this problem (it’s a fisher price.) thankfully we have two swings but he seems to prefer this one 🤷🏻‍♀️