I need the part # for a belt pulley on the bottom of the Sony SVO-1450. I believe it is for the rewind belt.

Check the belts, inside the unit you should see a rubber belt which is what pulls the tape fast forward or rewind. Some belts with time get loose and slip, they can also break and fall off which will not let you fast forward or rewind.
Open your cassette player and look where the plastic pulleys are located and check for the belts, they might not be broken at all but very loose and slip on the plastic pulley.

Adjusting aircon belt on HZJ75 motor.
1 Loosen bolt at centre of idler pulley. Idler pulley is smaller pulley adjacent to the Aircon pulley.
2 Rotate the adjuster bolt clockwise to tighten belt. The adjuster bolt head sits directly above and behind the idler pulley.
3 Anti clockwise will loosen the belt. Wind to end of the adjustment to remove or replace belt then rewind bolt clockwise to required belt tension.
4 Retighten bolt at centre of idler pulley following any adjustments.

It sounds like the belt is slipping or broken which monitors the speed of the tape movement. When you play or rewind the tape, it thinks the tape has reached the end of play and shuts off. You can try a different tape to make sure the tape does not have too much tension on it. If the second tape has the same result you will need to remove the top cover of the deck to inspect the tape drive mechanism. Make sure the belts and pulleys are clean and replace any belts which have glazing or cracks. If the belt is broken you will need to replace it with a compatible belt of the same length and width.

Hello,
My name is Dane and I am going to help you solve your problem. You said that the "Pulley" is loose when the blades are disengaged. I hope you meant that the belt is loose, because the pulley should never be loose. If it is loose, you should remove the pulley and make sure the KEY inside the center hole is still ok. Sometimes when the pulley gets loose it chews up the KEY and allows the pulley to turn on the crank. If the KEY is ok, just reinstall the pulley and tighten it.
I believe that your belt is probably just stretched and worn. The mower deck belt gets it's tension from lowering the mower deck. the lower the deck the tighter the belt. Just replace the belt. I hope I've helped! Thank you! Dane

Are they them that you press plastic with your finger and it pushes on a contact switch? If they are you can get away with just melting the plastic back in place with a soldering iron. You will need to remove the pannel to do this and melt from the back.

Since you have already removed the rivets, just go to the numbered portion of the instructions below and follow them to replace the rope.
To put the recoil assembly back on the blower housing, you will need to obtain a pop rivet tool and rivets or or 4 very short machine screws with lock washers and nuts and insert them from inside the blower housing so the flywheel doesn't hit the ends, and tighten them securely

Here is the instructions DIRECT FROM BRIGGS & STRATTON:

This is a relatively simple process, but you have to be VERY careful when doing this. The spring is long, under some tension and has sharp edges. Anytime you are dealing with the manual rewind starter assembly, there is risk of the spring coming out and possibly injuring yourself or others. If you do not feel comfortable performing this repair, I strongly suggest visiting one of our many authorized dealers in your area and have them do this for you.
You will have to remove the gas tank to get at the rewind and blower housing. Remove the entire blower housing and rewind assembly and turn it upside down.
NOTE:You do not have to drill out the rivets to get to the back of the rewind assembly. This is only necessary if you are removing the ENTIRE rewind assembly, (metal housing and all) and are separating it from the blower housing.
You'll need a pair of vise grips or a screw driver, some rewind rope, a long thin sharp tip flexible object (the wire from a coat hanger may work) and a lighter handy.

1. Take the pulley and start to turn it so that the rope becomes loose.
   
2. Remove the rope.
   
3. Once the pulley is all the way out, with the most tension, either use the screwdriver between the spokes of the pulley, or use the vise grips to hold the pulley in place; be careful not to place too much pressure on the vise grips, the plastic pulley may break!
   
4. Make sure that the hole in the pulley lines up with the hole on the rewind assembly.
   
5. Using the wire from the coat hanger, push the rope through the hole of the rewind and pulley. Pull the rope through the pulley and tie it off. Now use the lighter to burn the end of the rope to prevent the not from coming off.
   
6. Now, remove the screwdriver or vise grips, while holding on to the pulley.
   
7. SLOWLY let go of the pulley and the rope should feed back into the pulley as you do this.

Here is the instructions DIRECT FROM BRIGGS & STRATTON:

This is a relatively simple process, but you have to be VERY careful when doing this. The spring is long, under some tension and has sharp edges.Anytime you are dealing with the manual rewind starter assembly, there is risk of the spring coming out and possibly injuring yourself or others. If you do not feel comfortable performing this repair, I strongly suggest visiting one of our many authorized dealers in your area and have them do this for you.
You will have to remove the gas tank to get at the rewind and blower housing. Remove the entire blower housing and rewind assembly and turn it upside down.
NOTE:You do not have to drill out the rivets to get to the back of the rewind assembly. This is only necessary if you are removing the ENTIRE rewind assembly, (metal housing and all) and are separating it from the blower housing.
You'll need a pair of vise grips or a screw driver, some rewind rope, a long thin sharp tip flexible object (the wire from a coat hanger may work) and a lighter handy.

1. Take the pulley and start to turn it so that the rope becomes loose.
   
2. Remove the rope.
   
3. Once the pulley is all the way out, with the most tension, either use the screwdriver between the spokes of the pulley, or use the vise grips to hold the pulley in place; be careful not to place too much pressure on the vise grips, the plastic pulley may break!
   
4. Make sure that the hole in the pulley lines up with the hole on the rewind assembly.
   
5. Using the wire from the coat hanger, push the rope through the hole of the rewind and pulley. Pull the rope through the pulley and tie it off. Now use the lighter to burn the end of the rope to prevent the not from coming off.
   
6. Now, remove the screwdriver or vise grips, while holding on to the pulley.
   
7. SLOWLY let go of the pulley and the rope should feed back into the pulley as you do this.

http://www.bcs.tv/store/model_detail.cfm?id=12494

Click the link on that page that reads Additional Model Brochure Information

it might have a timer set on it.. see if it is.

if the square belt kinda serpentines in and around a couple pulleys (or did originally) then it did not get put back on correctly. try to think of another way it could be threaded through the pulleys.