My friend Hatchet Jack has a Tulle musket for which he has ordered a spare lock, and three spare main and frizzen springs. He does not like to be handicapped by a broken spring, though he has only had a couple in all the years he's been shooting.
Anyway, in buying the replacement springs, I found that there are not two the same as far as spread of the leaves is concerned, and so I heat to red and reshape them all, then harden and temper. I just did one last week for his "Taylor Made" Tulle as the frizzen spring was allowing the frizzen to rebound, breaking his brand new flints off at the jaws. When I saw him yesterday on the trail, he was ecstatic with the lock's performance, and also a perceived increase in his accuracy with the gun.
So Tom, I'll bet you just have to spread the leaves a little to increase tension in the open position, and all your worries will be over. Yes, all.