I would sugest to unplug the gearboxes and do sound' only until we have that dialed in
I dont have any 4 ore 6ch boards here atm so I must find a few older videos I did when I had ( + the one I already posted )
If you can set radio to mode1 so you have the same channel output as I have written on my radio in the video
as an example . On mode 2 you have ch3 and 4 on L stick if I'm not mistaking , So if you go the the tk60 page I linked to, and have a look at the 6ch setup, you see you need to use both ch3-4 to start the tank
that means on mode 2 ,on L stick, slightly down from center , and flick it Right .
Now if you have it in mode 1 as in my video you have ch 3 and 4 on seperat stick's , and need to use them both. Again ch3 slightly down from center , and ch4(L stick) flick it .