Im not at my own pc right now but if you have s3d (which im guessing you do), try this.
- Open the 7c1 turm dat with s3d
- find the node called something like turm7c_1_conning7c_high
- expand that node and select the 3dmodel (node #42 IIRC)
- right click and export that 3d model and its uv2 channel as obj files to your desktop (or wherever)... make sure in the export settings that pop up that you have "export to obj (others)" selected under the map channels option and that both turm###.obj and turm###-uv2.obj are ticked then export.
- now you can right click on the 3dmodel node and delete it from the dat
- reselect the parent node of the model you just deleted (turm7c_1_conning7c_high)
- right click it and select add new child chunk > 3d model
- select the model you exported (the ###-uv2.obj file will be seen automaticaly) and import.
- If you get a popup asking about importing normals select yes
Deleting and then re-inserting the 3dmodel node in this way will give a totally new mesh ID and the game sees it as a whole new model, it should solve the black tower problem... hopefully.