help from a newbie

[judgeshock]

Hi guys I have just built a venom crawler. I turned battery on and the servo im using tried to drive the wheels until it stripped a metal gear.

I can replace this however i'm worried it will do this again.

I have unlocked the diff locks and the wheels spin freely, when I put it on the ground to free move the vehicle everything seems really tight and it's a big strain even tp push it.

Has something broken in diffs? do I need to pull apart also?

I have had a look in gearbox and everything seems to be spinning ok.
Any ideas would be fantastic, thanks for your help.

Also are there any better diffs available on the market?