I've had a vibration problem that starts at about 3,400 RPM and disappears at about 4,000 RPM since I rebuilt it five years ago. Its engine for sure, but it rattles the trannie something fierce. I hope its the flywheel or the front damper, no sign of the damper separating between the inner metal and the elastomeric connection to the outer part of the damper. So I'm off to the rebalancer tomorrow to see. I sure hope its not the new Venolia pistons, they were supposed to be balanced when they were cast. Hate to tear into the engine but we'll see. The flywheel had been turned so many times that it was too thin, so the machinst cut a piece of 3/8" steel plate and welded it to the old flywheel and turned and re-balanced it (new and used good flywheels are NLA). I may have to pick your collective minds on engine component balancing. Sorry, but don't get the support that I do here on the Aston Martin website. As you can see, when I tilted the engine after I removed the front damper I had an Exxon Valdez moment.
