SBE won't load shell into chamber

[PQHunter]

After shooting the first round, my early model LH SBE will no longer lift the second shell from the carrier up for the bolt to push into the chamber.  The gun has fired many thousands of rounds and has been nearly flawless for 2 decades.  This is not an issue with shell size or the load of the shell.  The fault occurs even when manually cycling loads.  The recoil spring is new and the magazine spring is also new.  All components of the gun are clean.

Any insights?

[remarkable]

This sound like your carrier spring and plunger are not in the correct position in your trigger assembly.  Did you disassemble the trigger group at anytime recently.  Are you saying that when you remove your barrel from the receiver every shell is falling into the chamber without obstruction?

[PQHunter]

I have not disassembled the trigger group.  No obstructions, if I give even a slight tap to the carrier when the shell is sitting on it the shell will go up and the bolt will move it into the chamber.  The carrier does seem to be sitting lower than it once did and lower than my M2.