I'm not sure I understand. You burned out the stock motor with a 36v controller? Others who understand this better might offer something, but I'm thinking when you overclock the motor and go uphill it starts trying to seriously suck some amps and just can't because the wattage is already used up on the volts. So it sort of overpacks.
If you have a 36v controller already, does it still work? Is it a Currie 1,000w?
Your seller offers the 800w motor for $72 but the 1,000w is $819. Something is wrong, he might have meant $89 and doesn't notice the 1 in the middle. Except with the controller and throttle it's over $1,500. Totally ridiculous.
My advice is if you're doing some serious hills as it sounds, go to 1,000w or better. http://www.monsterscooterparts.com/36-v ... ndard.html
It's going to cost you a lot more to keep replacing parts.
http://www.monsterscooterparts.com/36-v ... y1020.html