Coletrains,
Thank you! I now have a working fore gun! I've had this problem both with and without TM 1.6, and you have helped me at least get it working!
A thought for you (this worked for me): I replaced the stern gun with a fore gun in my game, letting it take away the slots. Then I followed your directions for swapping the crew. My crewmen's data was in the "Compartment 7 ...AdditionalRepository" slots.
It already had the gun mounted correctly, so all I had to move was the crew slots.
Again, THANK YOU!