repair or renew saw motor?

Hi you D.I.Y's
Can you help, I own a cross/cut. circular saw, namely Stayer SC 381 type. Well I accidently allowed a piece of Oak wood touch a moving blade and same kicked back on me. After I tried to restart my unit, only to find that the saw blade jitters stops jitters stops, and so on. I think damage to the motor has taken place. Has anyone had similar circumstances? if so did you mend fault? plus to where can one purchase these motors!
Thanking all for reading my plight.
Jack.