Jake,
I found the Samson old double-braid eye splice directions, and didn't get any good answers for myself from it.
- It is for double braid rather than parallel core inside a braided cover (Samson doesn't make a product like Sta-Set X that I'm aware of).
- When I compared it to their "normal" instructions, I didn't see a difference in the lengths/positions to use. I might try reading it again.
They did have some interesting suggestions, including getting the line wet. I did wash the line very thoroughly (in a bucket of fresh water with first some soap and many rinse cycles, using a (clean) plunger to force water through the line.
I'm still wondering what I'm doing wrong (if anything) and how to make better splices in this line.