Looking for new Mini

I received my stuff from Impakt yesterday (had to pay 90€ extra on customs -damn).

So I now have a Medusa 3300 but I noticed that the 5mm shaft is round and has no flat piece for the grub screw. Did yours also come completely rounded?

So I need to replace the chassis, install the motor and my new Traxxas All Star wheels + Anaconda tyres. Still have to do the body.

Concerning the diffs : I'm going to put Green Slime around the O-rings and maybe on the inside if the diff gear where the gaskets sit to prevend further leaking. Would this affect the diff action ?