I've seen questions on this form as to what is the best way to reassemble the extremely difficult to install Insert which contains the Stirrup (includes hammer), Mainspring and Mainspring Plunger on all Model 52s. Once you've have reassembled the pistol and are about install the insert, make sure the hammer is in the 'fired' position. Reinstall the Mainspring and the Mainspring Plunger onto the Stirrup. Place the assembled Stirrup into the base of the Insert. Take a small plastic serrated tie and attach it around the base of the Mainspring just above the Mainspring Plunger and pull it tight (see pic below). You'll now be able to easily push in and reinstall the insert into the rear of the Model 52 frame. Once finished, simply cut the tie and remove it.