Hour-Strike Stop-Lever Spring
This little gem is perhaps the simplest spring on the front of the mechanism - a long, thin piece of brass. All it has to do is put just enough pressure on the stop lever so that it will rotate clock-wise and stop the hour-strike fan from spinning. Minimal tension - very fine little spring.
OK - that is the good news. Bad news? Often folks have "adjusted" this little gem. It is meant to lay just a few thousandths of an inch off of the front plate - so it is not rubbing the front plate, and so it does not rub against the quarter-strike rack (which rotates just in front of this spring). Once bent it is truly an art-form to get the spring back to where it lays just above the plate, and below anything it might rub against. Having just spent several days trying to remedy a quarter-strike problem, I can promise you even a slight rub against the quarter rack can give you fits.