Torsion dampers are common on such in one or both ends, not necessarily a part of the motor drivetrain but attached outside. Reason for asking is that this is a part with limited operational life that require frequent maintenance or inspection depending on type eg. a few years or so and not always cared for.
Next question, did you check the floor mounting? Rubber feet or shockfast type of mounting? Is it the same looking on all 3? Including the steelworks, any cracks or similar?