I was able to loosen the so hard to get bolt without removing anything. My right hand fit down there with a 13mm 6 point Tekton wrench I ordered from Amazon (cost me about $22 total). I used my torque wrench for leverage and extra length since the wrench is not long enough. Years ago I made the rookie mistake by using a 12 point wrench. Started rounding off the corners of the bolt. Tekton claims their wrench grabs the flat part of the bolt not the corners. Plus the swiveling head helped too. Well, I’m happy with the result.