I would def start there but also feel with your gloved hand.
https://apps.apple.com/app/id1089589547
I use this app for vibration measuring.
It will give you the vibration frequency which can determine if it's something that happens once per 720° (one cylinder power stroke issue) or 120° (every power stroke).
You can also hit a suspect like the cat and measure the Hz etc.
–awr–
Using Tapatalk VIP on iPhone