Replacing a missing O-ring in the breech end of the barrel is the common fix for a "puff of air" when the gun is shot. If the operator fires a Marauder without the bolt being closed, this O-ring can be forced out. Since this did not fix the gun, it needs to be repaired by a Service Station or returned to Crosman. All other repairs that may fix this issue will require disassembly of the gun and unfortunately is not something that can be explained over the phone.
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