So my daughter now 10 years old was a grumpy baby. That's an understatement. Those little mechanical swings did nothing to help. So I plugged an eye bolt into the ceiling (find the stud!) and took a shoulder sling and wrapped it around the handle of the car seat.
Now I took a long daisy chain and girth hitched it to the eye bolt and cliped the other end to the sling on the handle of the car seat with a locking biner. Buckled her in and I could sit on the couch and just give her a swift push and she would just swing for 5 minutes and then I would just repeat. Best thing ever! She loved it! Not rocket science but ho man it saved my sanity.