Now I realise it could be caused by a few things and googling lists anything from the rotors being installed incorrectly to bent shafts, etc, etc. Given it flew (so I'm told) before the upgrades and that's all that has been done to it, what would be the first things to check? I'm hoping it might be something obvious that the previous owner stuffed up when "upgrading" it

If anyone has tips before I start pulling things apart and possibly going down a very deep rabbit hole with no idea I'd really like to hear them.
TIA
