So when I wind the curtain to its highest setting, it'll wind enough to where I can see the 1/8th mark, but not enough to lock into place, so when I let go it just rolls back to 3/8th. Any ideas?

The most common cause is someone had it apart and set the curtain starting point 1 gear tooth of the top roller low. Another possible cause is the curtain has swelled and is too thick to operate at the current wind to top roller setting.
Another is too much curtain is attached to the lower roller. The normal is the curtain is attached to 1/2 to 3/4 of the lower roller.

Before tearing into it set the tension to High (six), wind the curtain to its smallest aperture then run down to closed after open 10 times. This is called packing the curtain. It will loosen with use and needs to be packed on occasion.

So I played with the position of the curtain and it still won't roll to the highest tension, there also seems like plenty of material on the bottom curtain for the 1/8 to wind up and catch. I tried "packing" the curtain as well with no luck. I suppose the curtain must have swelled too much? One thing to note, when I shake the camera I hear a metallic sound ( the only way I could describe it is a metal needle or paper clips being swished around in a ceramic bowl) seems to be coming from one of the rollers. I haven't disassembled the rollers and I'm pretty new to this, but have seen pictures where there are springs in the rollers, could something be wrong with the spring?

https://drive.google.com/file/d/0B1sPJkp-MdghRkRId1EwT0dpNkk/view?usp=sharing
My Grflex SLR shutter information / repair instructions.

I assume you have the back off the camera. Is the curtain dragging on the top housing when you approach the 1/8 aperture?
When you reach the limit of the wind when approaching the 1/8 aperture can you pull the curtain up further?
If the tension spring were broken you likely would not be able to operate the shutter at any aperture.

If there is a plate on the bottom rear of the camera remove it and inspect the tension roller.