Can you be more specific about what is wrong with the reel? Is it a continuity problem (if so, in which line(s)), or is it a mechanical problem (extension/retraction of the cable).
As Don has noted, Uhlmann turtles are the embodiment of most stereotypes about German engineering-- good quality materials and assembly, normally quite reliable, but also needlessly complicated in a number of places and time-consuming to take apart for repair. Basically, to get at most of the key elements inside the case, you'll need to remove a number of other screws and parts beforehand. Fortunately, my experience is that the vast majority of continuity problems with them are in the body-cord coupling or immediately behind it (i.e., stressed cable coming out of the plastic block). The A and B lines are brought in through the sealed
Mercotac, and the C line from the base-plate through the spring and shaft bearing, and both of those paths are normally very reliable, especially in comparison to the brush-and-commutator system of the LP reels.
-Dave