Vibration issue (damper plate)?

I’m sure it's been asked, and it’s hard to answer without seeing it. But this weekend I hit a stump I believe going very slow. Had a bad vibration when I gave it throttle so I backed it off and limped it back to dock loaded on trailer to find no visible sign of damage on prop. I had spare prop but it was late in the day so we went home. Next day I hooked up my fake a lake and spray nozzle for shaft bearing started boat and prop and shaft look fine. But I heard a knocking coming from bell housing at low RPM and stopped when raised. So I’m confident the damper plate is going. My question is would this be causing vibration? Or should I change prop take back to lake to see if vibration is gone? I’m going to change out damper plate but want to know if I should see if prop is out as well? Or could I possible have other issues?

I dont think the damper plate will cause vibration, but a prop does not have to be out much at all to cause vibration. Change the prop and drive it, change your damper plate this winter. It's a pretty simple job.

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Take the prop off and place it on a flat surface . Make sure all the flukes touch at the same place on both sides. Look at the strut and shaft make sure they are centered in the shaft log. With the prop off and spinning make sure the end of the shaft is true.