The Double Braid Splice Blues

[seawolf]

Hello all,
Maybe someone can offer some advise.
I am attempting my first double braid splice and after reviewing the Brion's video which makes things very clear, I seem to have run into a problem.
Here's the scoop.
I am using Brion's splicing wand and 3/8 inch sta-set.
The label on the wand states best for line 5/16 to 1/2 inch.

The problem:
I can not seem to get the wand to slide between the core and cover no matter what I do.
I even tried putting it in where the core comes out and going in the other direction to ensure I haven't snagged the core. There just seems to be not enough room and even bunching up the cover does not seem to help.
The line just jams on the wand and I get no more than an inch into the cover.
The line is not new, but only a season or so old.
Is sta-set a typical double braid? Do I need a smaller diameter wand?
Thanks for your help.
Bob