Oiled Longbow string aquisition
“No plan survives contact with the enemy” – Helmuth von Moltke the Elder
You mean the “Machined Longbow String”, right?
https://wiki.guildwars2.com/wiki/Machined_Longbow_String
I think you have to actually kill the dragon and then loot the chest/pods afterwards. Did you just open pods without actually succeeding the meta?
Here’s an older discussion:
https://www.reddit.com/r/Guildwars2/comments/3sv9jr/the_component_for_machined_weapons_that_drops/
People suggest that you get the other collection items first.
Herleve – Ruins of Surmia
Once you’ve got the collection unlocked (which you do), just do the meta once. You’ll get it from the end chest most probably.
It has a 100% chance to drop from the end chest of DS if it’s the only collection active, otherwise you might get any of the collection pieces.