Scooter Hub Rusted Inside

Hello. I'm new to the world of electric scooters and purchased 2 used ones the other day. I was told they were new in 2011. One runs, the other I discovered got moisture inside the hub, and is not turning, and I accidentally cut the wire trying to open it. Can't find any info as to maker, other than everything is from China. These when sold new were named Crazy Cat Scooters, by a person near San Diego who has a FB posting, but won't return my calls or e mail for questions, and is no longer in business. He lists these as having 4-12 volt batteries, but each scooter has 2-12 volts at 12ah, and there is no room in the zippered cover for more. Controller indicates 48 volts. I'm not sure where to find a replacement hub, but I think it's a 350watt. Could I go higher? I did a charge on the running scooter, and I rode it up a fairly steep road, but several power lights darkened, until I leveled out, and then all power lights returned. The front weel spins a bit upon exceleration, so I'm mostly looking for longevity for a level ride. Any ideas are appreciated, as I've looked at some posts, and know there is a high level of knowledge here. thanks Doug

in my short time I have ascertained this. the controller is exactly that, your motor is only rated at a certain wattage, but probably will take more. The battery is simply a power source and it will 'sag' under load which is why you are seeing lights go out climbing hills.
Most controllers have a low voltage cutout so your 48v controller must have 4 batteries connected to it.
350w-500w hubs using a 16 inch rim are very common on a lot of scooters and you should be able to pick one up for a few bucks, I gave my old ones away. The controller you have pictures is a 15amp max meaning around 7.5A continuous, 7.5A times the voltage (48v) is 360 watts. The 500 watt motor will see the same power as the 350 watt one and be pretty hard to see a difference.
For more range at the same speed you need more Ah and as your stuck on room as it is going tot he 20Ah format batteries will not be an option. Most encourage the move to lithium type cells for increased range, increased life span, reduced weight, reduced size, the initial cost is a bit more than replacement batteries but in the long term no one has ever gone back to SLA (Sealed Lead Acid).
Any change now will mean changing quite a few things so decide if you are ready to buy a new charger is you want higher voltage or to go lithium as they need different charger types to. Higher voltage past a certain amount will blow the controller so if you go past 52v then you are also looking at a new controller and the wiring will be at its max. Its a slippery path from there on.