The older PT92's are pretty simple. Similar to changing it out on a Beretta. Go to http://beretta92fs.com/ and click on "Removing mainspring (changing for 'D' spring)" for a video on how to do it. The newer ones with the internal lock I hear are more difficult to do but I only have experience with the Beretta's and older Taurus'. I have heard there is a second pin to knock out above the lanyard, but it releases some very small parts which can easily be lost and difficult to get into place for reassembly. Just pay close attention to the arrangement of things when you take it apart and be patient and all should go well.