I would first check for burrs or overall roughness of the extractor. These can have sharp edges and they will "bite" into the case and inhibit proper function.
My last 223 was a STS version and when I had to I stall new parts the replacement was AWEFUL in this regard. Couple minutes with my dremil and some flitz fixes that right quickly. BE careful, your not Tring to remove material other than any burrs. Just smooth the outside corners where the radius may bite as well as where ever the brass case touches/ bears against.
The edge that grabs the rim of the case SHOULD be a little sharp so it will not jump the rim once action is reopened. ( It SHOULD jump the rim when closing the gun.)
The action of the extractor has a bit of a cam to it, allowing the extractor to drop a bit when open for easy incertnion of a round. But when closed its held up. then remains help up for the inicial opening of the action just after grabbing the rim. very quickly that drops away and its all the springs job to stay in contact with the rim. If you take too much away from that spring you will develope extraction issues.
As a rule I NEVER cut a spring unless I have another in hand. Go slowly.
Good luck,
CW