Trigger problem with an Echo 1 G36(c&k)

[Remagoen]

The problem: When I go to fire, I must pull (most of the time jam) the trigger all the way back hard (VERY hard where I'm straining finger muscles, and a lot more than I had to originally). Sometimes on full auto, it stops firing.

What happened: So I was tired of being outclassed by some of my friends when we played outdoors with my downgraded (for a CQB arena) G36C. I got several G36K parts, including a tight bore, and I wanted to throw my original stock spring back into the mechbox. I am still new to cracking those things open, but I closely followed mechbox.com's instruction video.

Upon opening, I cleaned out and reapplied all the lubrication. I noted on the trigger block contacts that there was something black on the metal where the contact takes place. I wiped it off to ensure a clean connection, but when I did, it seemed more like an oil than dirt. I paid it little mind.

Upon reassembly (the first time) I forgot the trigger spring and so it was wobbly and didn't want to return to it's original place. Taking the box apart again, I accidentally ripped one of the red wires out of the trigger block and broke it.

My father helped me fix this part and soldered it back into place, and helped me reassemble the box again because of the need for 10 hands. A few more mods were needed to get everything to fix together thanks to the wire fix, as the selector plate didn't have free room to slide. With a final fix, the safety switch is stiff, but absolutely workable (and seems to be better too because it's not loose any more!).

Could it be the dark oil I rubbed off? Or is it something else?