RE: Balsa trainer rolling left on take off ?
Sure,
I like to have a helper but you can get the idea by yourself.
Use one finger to hold the motor shaft or spinner and then use the other hand
and put a finger under the rudder or very close to the end of the fuse.
Then lift it up and see if it will tip one side or the other.
You of course want it to stay put just perfectly balanced.
You may be able to balance it by just moving your battery.
Sometimes I have to add weight to a wingtip or close to it.
I hope this makes sense.