Motor to my electrolux centralvacuum has burned out .Is it a good idea to just replace motor?

Check the motor compartment to clean out dust if needed, motor brushes, relay and filters. It's a good idea to service your power nozzle once a year too.

Maybe, the brushes and commutator are alreay worn off. Best bet is to replace the vacuum fan motor.

The motor is burnt out. Good news is that most central vacuums are really easy to get into so replacing the motor shouldn't be too hard. I haven't worked on that exact machine but the fault is unmistakable.

You need to have the vacuum cleaned out. If you are good with tools, just remove the motor and fans assembly, take the fans off and wash them. Brush ALL dirt out of the housing and reassemble. Your Electrolux dealer can do this but it isn't cheap. I used to be the service manager for my area. Since it isn't under warranty, you can have ANY reliable vacuum cleaner shop give a good cleanout. NEVER put anything into the cleaner to make it smell good. Electrolux cleaners get their power by having a straight through suction. The air goes through the motor. Adding smelly things can crystallize onto the motor and burn it out.

With the smell and the noise, it's likely the motor is shot. Unless it's seen heavy use, this is unusual for an Electrolux of this age. Or it could have been used to vacuum sheetrock dust, glass, or even liquids, possibly without your knowledge. Or "made to fit" bags were used, allowing more dust to get inside the canister and into the motor.
Unless other parts/accessories need replaced, it's much cheaper to have the motor replaced than to buy a new vacuum.
I recommend taking it to the nearest Aerus Electrolux store for a definite diagnosis (should be free), cleaning, and repair if needed. The technician will also let you know what other problems there are.
If you leave it for repairs, make sure you are given a copy of the work order for the vacuum that includes: type and model of vacuum, serial number, accessories left, your name and address, and an estimate. You'll need this to get your vacuum back. It's a good idea to also have this information written down at home.

If the smell is like burning metal and very strong, the motor is bad and needs replaced.
The circuit board inside could also have shorted and burned out. You can check the motor by removing the low voltage wiring from the side of the vacuum and using long-nosed pliers. Open the pliers and slip a point into each terminal. The motor should come on if it's still good. If it does run, the problem is with the relay board.
Although you can get either motor or board and replace them yourself, if you let the tech at an authorized Aerus Electrolux store do it, there's a one year warranty on the part/s and labor.
The nearest store can be found using the following link.

http://www.aerushome.com/storelocator/

The motor is probably burning out, or has. Smell the exhaust port. If the odor is especially strong, here, then that's the problem. You'll need to take the vacuum to the nearest Aerus Electrolux store for definite diagnosis and repair/replacement of parts.

http://www.aerushome.com/storelocator/index.cfm

check the wiring it might have gone bad

If you go to aerusonline.com, there is a dealer locater function that will allow you to find the nearest aerus electrolux store. If there isn't one local, I would call one of them and have them ship it to you. You may be able to find an aftermarket motor on line, but there are several different models so you may or may not get the right motor. Good Luck!!

If it tripped the reset again, I would probably agree with you. Check out centralvacuum.com for another motor. They aren't the cheapest, but they have excellent support. Good Luck!!