ok, I have a few questions; First, is this a four stroke or two stroke engine? I will assume you have a four stroke GY6 based moped or scooter. The GY6 design is one of the most common. Second, I’m not sure you are naming things correctly. The hose the comes from the crank case (should actually be the valve cover) should go to the airbox (air filter housing). The other thing that can be done with that hose, if you do not have an air cleaner is to use a breather of some sort. You can just run a long hose, placed higher then the engine and open to the atmosphere. Just keep in mind, not just crank case gases come out of the hose. When run hard, you can get oil in that hose as well. What are you calling a carb overflow. Is it the hose coming from the bottom of the float bowl of the carb? If so, that’s a float bowl drain. You open a valve at the bottom of the carb (in most cases) to drain the carb so you can store it, empty.

do both drive wheels have the rubber intact? To me it sounds like one is missing. You could also have a motor that is a little lazy or debris on the magnet clutch in the gearbox. If the rubber “tracks” on the drive wheels are intact, I would make it run for a while with the drive wheels off the ground and make it go thru a few “forward + 99” commands, and see if the clears the clutch and gets the gearbox to move more freely Aside from that a complete teardown and cleaning of the gear box, which is very involved.

This sounds like the motors are stalled. I would turn the drive wheels by had a bit and see if it frees up. Make sure you have fresh batteries in it. These things were battery hogs.

sounds like the motors are stalled. I would work the drive wheels back and forth by hand and see if that frees it up. Also make sure ALL the batteries are fresh. These are real battery hogs.

I just picked up one of these with a similar problem (although mine is a bit more terminal, but I purchased a second one for parts)…. Pulling the gearbox is a pain, getting into it is even more of a pain. However, you need not take the wheels off to get it out; although the two wheels attached to the gear box will come out with the gear box. First, remove all the screws on the bottom of big trak (should be six, some of them are between the wheels) Take the two hatch covers off the front next to the “proton beam” there will be screws under them. Take the 9volt battery cover off and gently pull the forward part of the “Cab” forward and up. The light socket will still be attached so be careful. Either unplug the light from the mother board or take the screw out of the socket so you can set the “Cab”, aside. Remove the 4 screws that attach the gearbox to the body. now remove the back, top portion of the body. You will need to unplug the motors, taking note what color wires go to what pins (note, the colors are...