Good evening. I just stumbled on this thread and I am trying to help my elderly father with his DP-600. A couple of weeks ago his return spring broke and when it did, the housing broke as well. We have a replacement from ebay but I am struggling on the correct process to remove the broken housing and install the new one. It appears from what I have seen, I need to remove the adjustment screw that is located on the bottom surface. If I do, will the old assy pull out so I can install a new one and reinstall the screw? Also do I need to preload the spring at all or just install it and adjust with the screw? I am sorry for the obvious questions but I am trying to help AND keep him from getting hurt at 93 years old.