stroker damper

Yours isn’t an outlier. Any time there is rubber in a damper it’s degrading from the first time it’s fired.

The harder it’s worked (longer stroke, more RPM, heavier bob weight or all three) the quicker it loses its ability to absorb crank harmonics. It’s the nature of that type of damper. They generate huge amounts of heat. That heat breaks down the rubber, and that changes the frequencies that the damper can control.

I’ve seen damper issues make bolts come loose, pushrod adjusters back off and all kinds of weird stuff. These cranks flex and twist a bunch. If that’s not accounted for bad things happen.