There are multiple possibilities. The simplest one is that it was reassembled improperly. There is a large head screw at the pivot point in the break open action. Use a dime or larger screwdriver to loosen this screw. The retainer that holds the cylinder in place will drop and allow the cylnder to be removed. This is normal for field stripping and cleaning. Replace the cylinder and the extractor star should retract, reposiion the retainer to hold the cylinder in place and tighten the large screw. Check for clearance and close the revolver. It should open up and retract. If it doesn't, there are other possibilities. In many 455s, the cylinders were shortened for using 45 Auto Rim or 45 ACP in moon clips. These shortened cylinders will raise the extractor but, they do not drop as they are modified from being able to function. They will retract upon closing though. Check for the inspection release function also. When the revolver is breaking open, there is a nub in the pivot hinge that projects outward, push in on it while opening and the extractor star will NOT rise. This allows one to see if the revolver is loaded without ejecting the cartridges. Someone could have attempted a repair with improper parts too. In particular the cylinder extractor spring. Try the simple things first. Visual inspection should reveal if it has been modified from its as designed specifications. Look into the chambers and see if they have been reamed, are the shoulders inside the chambers present? In 380-200 revolvers, it was popular at one time to modify/ream the chambers to allow 38 Special full wadcutter cartridges to chamber. The possibility of modifications is high.
