routing new external speaker cable.

Dealing with '14 388 daycab and new cobra 29. the plug for the external speaker(the stock one mounted just above the door) no longer makes a good connection in the back of the radio. My thought was I could pull the screws out that hold the external speaker in then tie the new cable to the old one and pull it through without having to pull out the headliner. Is this at all possible or is everything so tight up there that I'll just have to drop it anyways?

 

the speaker works fine, but the end plugging into the back the cb is loose and only works if I hold it just right. It's not the radio itself as thats new... Ive never solder before so dont know how putting a new plug end would go... Just thought of it now, that I guess I could just buy new cable cut off the excess wire and then just butt connect the new plug in that way...