I just had the shop take out the motor and replace the coulper. I noticed first time out today that there seems to be a chugging sound coming from the harmonic balancer and it doesn't seem to be exactly smooth, seems like vibration in the pulley as I have it at idle, definitely not smooth like my port motor.

Can a new coupler throw off the balance??? What might be causing this sound and the visual wobble look of the lower pulleys???

Loose balancer or broken hub on the pulley?

I'll check the pulley's and balancer by hand, to see if anything is loose.

Is it possilbe that it has anything to do with having a new coupler installed?

I definitely don't remember this sound or vibration before they installed it.