How can I stop the squealing noise in the motor on my Sanitaire wide track commercial vacuum? It's making a squealing the minute I turn it on

you will to take motor to motor shop, disassemble motor and take bearing shop, OR buy a new motor for less money
copy and paste link

https://evacuumstore.com/p-9980-sanitaire-commercial-upright-sc679-j-motor-assembly.aspx

There really isn't much to know about this vacuum in the owner's manual. It has attachments, doubles as a blower by attaching hose to back end. Practice the usual safety standards like don't use near water. Ck the prefilter on bag changes. That's about it.

Clog? Something in brush assembly? Bag on correctly?

Switch needs cleaned or replaced

When you take it apart, check the end play and lateral travel of the shaft in the motor that the fan connects to.

please go to :http://www.eureka.com/en-US/Customer-Service/Videos/ proeed with common sense. God bless you

Hi,

Vacuums are noisy, but shouldn't sound like a jet.....

Trying to find out what is wrong depends on what kind of noise it makes, i.e. high squeal, vibration, whining and where it comes from.

Here is a webpage with troubleshooting advice on noise in vacuum cleaners. Hopefully you should be able to track down the problem. http://www.ehow.com/how_7493926_fix-noise-vacuum-cleaner-motor.html

If you need further help with repairs, please reply back. Thanks,

Handie Andie

It could be a worn belt. Sometimes worn belts can cause the vacuum to make funny noises. I have listed a link to the owners manual and a link to the belt you need.

Eureka SC4580 Owner's Guide

Eureka SC4580 Replacement Belts

the bearings in the motor needs to be checked,
or the impeller is damage.

Does there seem to be good air-flow and suction? If not, look for a blockage somewhere. Otherwise (and more likely because of what you say about the sound), look to the brush roller. Does it rotate when the machine's switched on? If so, maybe the bristles are worn and no longer make contact with the carpet properly. If not, the belt that drives the brush roller is broken and must be replaced. Your Owner Manual will tell you how to do this.  Good luck!