Thanks guys.
I've already stripped the frame, so can't get any video of the play that was there.
Alan, I've just had a closer look at the main frames and noticed the slight elongation of the gearbox mounting holes that you mentioned. They were packed with dry Loctite so they looked like round holes.
![Sad :(](https://synergyrchelicopters.com/forum/Smileys/default/sad.gif)
I've cleaned them out and expect the spur gear clearance will be ok if I push the gearbox forward when I get to reassemble the frame.
You wouldn't want to see the amount of Loctite that's been used on some screws and nothing on others when this frame was built first time. That plus a gorilla working the 2mm hex wrench.
I'll let you know how it goes when I do the re-assembly.
Thanks for your help.