I finally have a maxi joker v2 to compliment my 2 other v1's and as usual have the problem with installing the grounding screw through the boom. Here is what worked for me that was very quick.
1. Hole in boom is already drilled to proper size, tail boom and belt intalled.
2. Remove 2 ea nuts and washers on the servo right above the hole unless they dont interfere then leave them on.
3. Insert a 2 ft piece of monofilament fish line from the top hole into boom, grab with needle nose pull out through side access hole over the top of the belt.
4. Clean the tip of your cap head screw with alcohol. Apply a small drop of hot glue to the end of it and attach monofiliment line, let cool.
5. Have flashlight, allen wrench with 90 on it ready, slowly pull the monofiliment back out guiding the screw to the hole, nudge with thin screwdriver, all you are trying to do is get the tip started into the hole, dont pull too hard. Once tip of screw is started use the screwdrive to push it up into place.
6. Once threads are through the top insert your allen wrench into the cap screw inside the boom and hold it steady while you put on and install the ground wire and nylock nut. Tighten nut to taste.