The 6 tooth pinion gear was a great idea - but the moster was still too fast for crawling
I decided to put an additional gear into the gearbox. The gear is from a tank, but you could use anyone you have from a zipzap. The gear has 7 and 19 teeth. I used a wheel pin from a bit for the axle.
Now i have a overall gear ration of 72:1, instead the stock 24:1
gear box modification
diets - you can never be too slow