I don't know the original post, but it could be that your transmission is frozen and the belt is trying to turn a frozen pulley. That would cause screeching and smoke.

Thank you for your suggestion. We think that you may be right. We have been able to get the manual and it points to that problem. Thanks again.

What type of mower do you have, what issues made you take it apart in the first place? Chances are you didn't put it back together correctly and need to go to the manufacturer's website to find a diagram and do it right. Can't help much due to no info included on your mower (not even the color).