I have also had a gearbox problem, unfortunately, not so easy to fix.
I had my Genesis LE for 2 weeks, was just finishing breaking it in, when the gearbox broke. It was having trouble shifting from reverse into forward, and then refused to shift into forward at all.
I removed the gearbox, and discovered it was FULL of sand. Presumably it got in through the forward/reverse lever hole. (Design fault I think – it should come with a grommet or boot of some sort). I live in a sandy environment, and have run it on the beach as well (being careful to stay away from the water and wet sand).
After I had gotten over the shock of how much sand was in there, I inspected the gearbox for damage.
There was a lot of damage.
GS006 (1 of the 2 main centre diff cogs - two teeth missing, not adjacent)
GS063 (shaft snapped at pin)
GS054 (shifter cog broken into 3 pieces)
GS069 (bottom end of shifter in many pieces)
GS086 (Reverse cog scarred, but not actually broken)

I sent an email to CEN (on the 2nd of Jan) but didn’t receive any answer, or even an acknowledgement of the email.
After an unacceptable delay, I decided I would just go get a new gearbox for it. Hopefully, a stronger gearbox.
So I ordered the GSS08 (Nemesis Gearbox). I figured I would do battle with CEN about warranty over the broken gearbox later. I planned to go away this coming weekend with the Truck to have some fun with some friends who also have RC Monster Trucks (Not CEN’s)
The GSS08 gearbox arrived yesterday morning. First thing I noticed was it was all in parts, not assembled as the illustration on CEN’s website shows. OK, I can handle that. I started to assemble it. Problem. Several parts are missing!
The Internal gearbox drive shafts are missing;
The Brake Disks are missing;
Some of the internals of the centre diff are missing;
There may be other parts missing, I’m not sure. It didn’t come with a parts list, or any assembly instructions.
I now cant take my truck away for the weekend (makes the trip kinda pointless...... thanks CEN.)
So, I emailed the supplier (XShobby) about this. No help, he has never dealt with the GSS08 before, so didn’t know anything about it.
I emailed CEN asking for confirmation as to how the GSS08 is shipped, and a parts list. No answer.

Does CEN usually take so long to answer emails? or just ignore emails?

I love my Genesis, but so far, the Genesis gearbox and the service has been less than stellar.
I’m thinking maybe they’re closed down for an extra week or so over xmas.

Has anyone else had problems like mine with the Genesis and with CEN?
I’m a patient guy, but my patience is starting to wear thin.
My Truck broke though no fault of mine.
I have been unable to contact CEN.
I decide to just get a full replacement part, and its incomplete.
CEN still [wont answer / hasn’t answered] my emails.

Anyone got any ideas? Suggestions? Helpful hints? Simular experiences?

Thanks... Raptor (Philip in Australia)

A small point to all runing a Genesis out there. Seal the Shifter hole. Sand getting in here has been the cause of my problems.