XRAY - Model racing cars

Hi
In the uk we run on used AstroTurf that comes from sports pitches (football)
When it’s used at these places they add sand to stop people getting carpet burns so you slide on it more....
However it is causing problems that the sand is getting into the gearbox and breaking the idle shaft gears and top shaft and the diff gear....
There seems to be a gap in the diff when the bearing is on the diff output
It is just not me there are a few of us at same tracks with the same problem....
I don’t really fancy having to fit new parts after each run ran yz2 on same tracks and no problem....
Help

I have the same problem whit my xb2c when i ride it on my locale out-door track. Small dust parts got in my bearings to. I must replace them all ready. The dust got in true the said of the bearing.