I've run this quest dozens of times or more and never had any issues like this. Across many hours of play (enough to earn 691 radiant crystals) in Shadow Haven trying to get my mom's (and an alt) toon their healing automation... I have only seen the 4 stones (pre-quest) and like 50+ each (no lie, maybe closer to 80-100) of the Focus Crystal, Lost Toolbox, and Chunk of Mythril...
But... NOT ONE Silver Cog, Bronze Cog, or Shard of Metal in 3 days.
At first I thought yesterday that maybe my ill luck was because there were 22 players in the zone (6 in my group) and I figured that could easily distort my odds (other looting groups). However, both the day before and today I was alone in there for hours plowing away. I pull between 20-23 and squash those trains in 30-40 seconds (about as fast as I can target/attack). I found the pull itself is about one minute. Graciously I can figure 2 minutes per pull + occasional rebuffs. I've spent about 14 hours in there now hardcore grinding. I estimate that is about 9,600 kills. I will say 8500 for bio breaks and eating dinner. I think anyone will agree that 8500+ Shissars should be adequate for 2 complete healing automatons.
I waited to see if it was just the worst streak of luck I ever encountered on EQ [ever] before posting here. I was able to much more quickly (like in 1/3 the time spent currently on HA) complete 5 WoS Murkglider pet quests. The WoS Pet usually takes much longer. Especially the Murkgliders with their non-existent plasma.

The fact that only 3 items have dropped as many times as they did (like 225 to 275 times for the Cogs and Shard [combined]) and the other 3 not at all leads me to believe that something is wrong.
I don't mean to be presumptuous here but is it possible to have Vaion look at this?
Has anyone else had different results?
I'll put this on the back burner until I hear back...