My belt broke and I cannot find a replacement anywhere. Can you tell me where I can buy replacement Sweep n Groom belts for my central vacuum system.

From the top side of the motorized nozzle, grasp the hood near the handle socket and lift the hood forward to remove. Lift the brush roll from the pulley end of the base to remove the worn belt from the brush roll. Replace the new belt around the brush roll pulley and return the brush roll into the base.
https://www.allegrovacuums.com/spare-parts/drive-belt-for-sweep-n-groom-powerhead-zas099-zas099-bt.html

you may have something in your brush bearing that does not allow the brush to turn easily thus stretching the belt. Chris

Yes it will. I had same problem. You need to replace belt. Bissel site tells you how and you can buy new belts from them.

You can buy that belt here:

BM1393 Belt

You can buy the belt you need here and view the manual which has instructions:
CT14DX belt and manual

Do you know the brand or model? If not you can get replacement central vacuum belts here:
Replacement Central Vacuum Belts

You can buy them here:
Replacement Vacuum Belts

You need to change the belt. When it does that it means it is worn. You can get replacement belts for it here:

Central Vacuum Belts

or here is

Broan Central Vacuum Belts

Burnt smell is probably the belt slipping. Even though it looks OK, either the belt needs replacement and/or the roller needs cleaning and/or lubrication at the ends. Try cleaning the roller ends first and then light lubrication with WD40. If belt works, you are done. If not, replace belt.