I have a Kavan Sopwith Pup slow flier that I have converted to brushless and LiPo power. It has been flying excellently, but recently the speed control has stopped working properly. I know if you overload it for long periods you can cause it to smoke, but in this case, I have been flying at only 1/2 to 1/4 throttle, never more than 3/4. Ihad just landed and went to takeoff again, but all I got was a lot of smoke.The motor is a small bell outrunner, and the speed control came pre-wired to it, before I salvaged them out of an old RTF model. They don't have any specs on the labels. I used the stock prop and battery (a 3s 1500 mAh) as well.
The throttle either doesn't work at anywhere below half throttle, and only stutters at 3/4 throttle, sometimes spinning the prop backwards. The ESCgets very hot, which I assume is not good.

What can cause a speed control to just die?I have had two brushed speed controls that have lasted for years with no problems.This one has only been run a few times. I'm worried that I have done something wrong!

Any suggestions are appreciated!