How do they show it being done upside down? Some planes are balanced upside down. Since it's a Biplane I can see it being done upside down, I would guess it's somewhere near the leading edge of the bottom wing.
I saw a picture of a TM being balanced with string attached to the rear cabanes of the upper wing. The instructions for my TM show it about 2/3 back from the front of the fake fuel tank.
On the 88" Ecomrc TM the CG is 146mm from the leading edge of the top wing at the fuel tank or about 5.8 inches.
The Hangar 9 Tiger Moth shows 6.5 to 7 inches and is also 88" wing span however this appears to be too far forward, the following is from anothe forum on the H9 TM.
"Guys I have been watching this thread a little and have been concerned about you having to add weight to the nose. I went to a lot of trouble to keep everything up in the nose and the tail as light as possible to ensure you would not have to add nose weight, or in worse cases very little nose weight.
I talked to Dick yesterday and he also had to add a substantial amount of weight. (Nice job on the ballast Dick).
For reference 4 pre production and one production kit was built and flown before we shipped, none had nose weight. As you can imagine how I felt when the first few kits that have been built by consumers we having to add excessive amounts of lead, I was pretty disappointed to say the least.
Well last night I pulled mine down of the wall ( the one I was flying at Joe Nall) and did a C of G check. Sure enough, the numbers in the manual are 1” too far forward. Mine is currently flying at exactly 8” measuring back from the LE of the dummy fuel tank, and I have flown it 3/8” further back than that. So the manual should read, C of G is 7 5/8” – 8 1/4'”.
Guys I sincerely apologize for my error, and I hope this comes as good news as you should be able to remove some if not all the lead from the nose"