Sworkz BE1 weird noise

[1993sei]

Hi

Finally got a motor and speed for the BE1.

Fitted the motor and powered it all up, the drive train sound rather loud, disconnected the front and rear prop shafts and it seems like the noise is coming from the pinion/spur gears. They seem to be meshing okay and I have tried to adjust the gap between the two from loose to tight into the spur, however nothing I do gets rid of the rattling, nothing seems to be binding though.

Is this just normal or am I missing something?

Cheers

Dave