Small Engines (Lawn Mowers, etc.): Transmission pulley for Yard machine riding lawnmower, transmission pulley, rear pulley

Question
Hi Michael,
I have a 2003  42" inch yard machine riding lawnmower. Model # is 13BT604G452. While mowing it suddenly began to make a screeching sound, I disengaged the blade and turned off the mower. Grass clippings that were on top of the deck were smoldering and the PTO belt was very loose. I replaced the PTO belt, cranked up the mower, engaged the belt and it made a horrific noise. I turned it off and looked at everything and didn't see anything. The second time I turned it on my son watched from the side to see what happened when it engaged. The rear pulley that contains the drive belt is sparking immensely. Upon a closer look at the transmission pulley (if I am reading a parts diagram correctly) it is very loose. According to the diagram there is a hex nut that belongs on top. I feel no such nut. I don't know if something has broken in the pulley assembly. I am not certain that is what is causing the sparks or if I should be looking someplace else. Should I replace the entire pulley assembly or is there another solution to the sparking and the screeching sounds that it makes when the blades are engaged? Thank you for your help.

Answer
Hi Aaron,

I suspect that the pulley is spinning on it's shaft or is worn and rubbing on an adjacent part.  The nut, as you think, may have fallen off.  You will need to inspect it closer and remove whatever you need, to see exactly what is happening.  Then you will know what is defective and can replace the needed parts.

Let me know how you make out.
Michael