Online Community of Zenith Builders and Flyers
The "washers" and the tubes were missing in the "engine kit bag".
A call to Arion Aircraft was enough to get the missing parts.
Plus, icing on the cake, a pair of rubber cushions - no charge - to replace the one I cut a bit too aggressively.
Something I learnt through this process: a phone call often gets things clarified and resolved much faster than email.