Manni,
We will have to work up the flight map ourselves. There is actually a lot of information in the file, spread among different pages besides what is on their 3 page version of a "map". I will start to work through it.
The gunner in the nose of the ship would have been the bombardier/navigator, Wolberg. If Koker operated the tail gun then the top turret gunner may have been Dwyer.
Here is a diagram for the bailout positions for a 7 man crew of a B-26.
https://www.flickr.com/photos/lightning72/3972129164
The 7th man (man in yellow) was a "tunnel" gunner that could move to either side in the rear of the plane and operated one of the waist/belly guns on that side. His position had been eliminated. So with a six man crew, assuming they are listing the enlisted men from front to back it may be that Samar was the radio operator, Dwyer was the top turret gunner and Koker the tail gunner.
Now that I know you can see the file, I will work up "our" version of the flight map and know I can refer to various pages in the file. It is the 2nd Box (with which Hopkins flew) that went off course on the return. They had a lot of trouble at the target.
Regards,
Rolland