Is all this just the initial signs of a worn fly and I just need to replace it, or am I missing something?
could be . but if there is wear it will show on the sear side of the fly .
without seeing it , it could also be gunk , oil or contaminants either in the pivot hole or on the back or outside of the fly ear itself .
See the fly works from gravity . So as your sear passes it , it falls on the inside of the sear nose .EVEN when the rifle is laid on its side . When the sear is tripped , it pushes the fly in front of it, IF the fly has not already fallen down in place over the halfcocked.
Once the fly has hit its stop point , the sear then rides over the fly , thus missing the ½ cock . But if the sear side of the fly ear gets warn it exposes just a hair of the half cock and the sear catches
Now what also can happen with some designs is that they have a sear and fly set up that only allows the fly to contact the sear in a very small area . In these cases if the inside or outside of the sear ear OR the outside edge of the sear gets worn then the fly cant interrupt . what happens is the fly gets pushed to far out during its rotation and the sear catches the 1/2cock .
The third thing that can happen is the fly forms a small burr . Like the first issue , you may not be able to see it with your eye , but its there . Its really surprising just how small a burr will cause the lock to stall . In this case what happens is you think your stuck at half , but your really caught on the fly .
So how to find out whats happening .
Take the lock out and slowly bring it to the full cock . The sear should have to have to move around the fly just before it engages the full cock . This movement is very slight and you have to look very close to see it .
Now slowly take the sear from the full and carefully let it slide back down . Keeping only enough resistance to let the lock fall slowly . You want to let it catch if it will .
Take not that the sear is pushing the fly in front of it and that the fly completely covers the ½ cock and that the sear smoothly slides over the fly .
If all looks well , pull the fly . Taking a cotton ball or Q tip and wipe it across the sear side of the fly . If you have a burr forming , the cotton will catch on it . . If you see the cotton catch , just a few light swipes of emery cloth will remove it .
If no cotton then us alcohol and clean the fly and its pivoted hole real good .
If you use oil then oil the fly only . Then wipe it dry . That will leave all the oil left on the fly that you need . Now put things back together