I found a place where u will find 100% a Goblin.
Tested on EU, Softcore, T1.
Start Act 1 Quest 10, Quest from beginn.
Port to Cathedral Garden
Go into Leorics
Go into Cathedral Level 1
Search for the Goblin
I aleady did 8 runs, all the time i found a Goblin on the map.
The only problem is, he is always on an other spot so u have to search on the complete stage for him.
But the Stage isn´t that big and often he is somewhere on the start of the map.
GL & HF