Follow up.
After several emails (they answered on a Sunday!), EME said they had a bad batch back in 2016 and thought they had recalled all of them, but apparently not. They stepped up to the plate and are sending a full replacement kit.
In addition to the damper, the pump would not pump when I attempted to put it back on the road. I pulled it out and got it working on the bench, but then it started blowing fuses - once whilst I was test riding it. When I took it and filter[/size] [/size]out of the tank this week, black gas poured out of the filter. Thinking a plugged up filter was also part of the problem.
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