Another two spots I found are on the cosmodrome, in the Rocketyard, pop an Ether Seeds, kill the servitor, leave the Hive, go to the other side where another servitor or the two fallen vandal majors spawn, back and forth. Also on the Moon, I think it's anchor of light area, not the patrol spawn area. There are two spots where a servitor and a Captain spawn, back and forth it. I say these spots because I noticed that the servitor will drop 48 or 49 glimmer each time it's killed.