Weak main spring on the right hammer could also be a possibility.
You should be able to compare the protrusion of the right pin with the left one to see if it is the pin. Several possibilities. Even if the right pin is shy on protrusion, you still need to check it for some Gunk build up which may be blocking the hammer's fall.


Miller/TN
I Didn't Say Everything I Said, Yogi Berra