I had the same issue when I did tried the same mod. I ended up messing up the antenna during the process. When I tried to fix it I ripped the antenna in half. I bought a wifi pigtail (see ebay link below) and routed the cable to the mast antenna hole and bolted it in. I then use a screw in antenna. Works great ever since. I run the original spektrum module. Not sure if the pro version will work with this pigtail, but it would not suprise me if they are the same style of input connetor.

http://cgi.ebay.com/5-SMA-Female-to-...item20af518b95