I would disassemble entirely and give it a thorough cleaning. I assume you have the manual for disassembly and reassembly. The first thing I would do is remove the trigger mechanism. Just tap out the 2 pins and pull it out. This assembly is a casting if it is an express and you may have a burr on your action release. If that's the case you will have to send it back. I wouldn't recommend disassembly ofthe trigger mechanism unless you are a compentent gunsmith. But if you don't see anything out of the ordinary, flush the trigger assembly liberly with gun degreaser or carburater cleaner, blow it out with compresed air if you have access to any and give a light coat of gun oil. Do the same for the interior of the receiver.