Recently I had to replace two latch springs on my 31 S/W. First the plate on the top of the door has to be removed. Un-hook the window side channel from the top and bottom, as this channel runs through the door latch assembly. Slide the channel up through the top of the door about 8". Wind the window up to near the top as far as possible. This will bind with the channel holding it in place. I did not want to remove the window or side channel as I thought there might be a problem with re-installation. The door latch mechanism can then be un-bolted from the edge of the door and the inside panel and lifted out. Sometimes you may have to unbolt the window regulator from the door panel to obtain enough access to remove the latch mechanism. At this point, you may have to use a soft-ended long jaw wood clamp to hold the glass and channel in the upper most position. The latch mechanism's usually need to be rebuilt with new pivot pins (obtainable from Snyder's), also the outside door handle socket in the latch mechanism, needs to be silver soldered or brazed in opposite rotational direction to restore the action. This will repair the sag of the outside door handle, which is common with this style. These latch mechanism's were not made by the Ford Motor Company. I have forgot the maker's name. Not a nice job, but after awhile becomes necessary.