Picked up a Traxxas in a vehicle trade recently and I know nothing about nitro cars. Ive always been into electrics. Well with my car I got a few spare engines and one of them was the Sirio .12 engine. He told me the main shaft is siezed up but I dont see how. The shaft at the base turns and I can hear the motor turn over. The carb operates like it should to so I am confused what the problem was with this engine. Can anyone give me a little background info on this engine and tell me how to properly check it out for proper mechanical operation? Any help would be appreciated. I will not be running this engine because I am happy with the RB Concept v.12 engine and backup 2.5 I have on hand. I may sell this Sirio engine if I know it is working properly.