clipping the spar flange is difficult. the piece of stainless they give you works fine, but filing the edge of the cut is tough, so little space to work. Take a cheapie HF file, they come in sets from India, hit it with a torch, bend, dunk in water to reharden it. now you can file using the inside radius side. I used a dremel disk for some of the cut, but it is difficult to complete the cut without hitting the spar web. I was able to score the remaining cut with a pointed die grinder, then bend and break off the last bit. I then filed the cut using this file.