I had an Encore with a extension on it. Though the Encore is gone, I think the extension is still in a box somewhere on my loading bench. It didn't take me long to pull it off! My rifle went from being okay to firing when it wanted to, like you stated. While it may be an issue with the hammer spring, which TC would probably replace under thier warranty, I'd try it without the extension first. I realize that a gloved hand can't get under the scope very well without it but it can be done.
Wonder if they can or would replace your original hammer with one of the new swingout ones? They knew they had a problem or they wouldn't have developed this new style hammer...Just a thought?
He took me!
Wish you were here.
Proud Parent of a Marine