My Makita ut2204 mixer unit has developed a fault. Brushes are fine, power is ok as the green indicator light on the grip is illuminated. Motor hasn't burnt out. Anyone have any ideas

Check that power is reaching the unit and that the on/off switch is fine. If all ok, then check to make sure that the brushes of motor are making contact with the commutator.

it is a armature problem common to makita products
replacing one armature with a new one does not solve the problem as the fault is a design fault
probably armature not wired heavy enough for continuous running
consider replacing it with a better brand that enables continuous operation

Try taking the bottom apart to see if a string or similar object is preventing the brushes from rotating.

Also you say you are getting power to the motor, what is the voltage to the motor?

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gregg_27a4d257e54e7920

may be the carbon brushes are short or motor connectors have become bad connection by moisture and dirt by use temporay a wrong filter sometimes its a very light and simple motor johnson motor with hammer brushes
DeWALT DC500 Type 1 Vacuum Parts

No diagrram is necessary unless you have dismandled.
Check if the brushes are touching the mtor commutator. If not you can easily remove both the brushes and polish the surface evenly .Insert only after cleaning the motor commutator till the copper shines.
Use can check for the continuity of the brushes to show that the armature is working Ok.
Now check the filed winding. Both the windiings must snot show any leak or short to the body. If so the motor is fault.
If field is ok with the resistance check then check for power supply to mtor when switch is triggered . If not check cord and switch.
Hope this tip helps.

check belt if ok .may be brushes motor bad....

The motor could be bad. Sometimes the carbon brushes will get stuck from the fine dust buildup over the years and will loose connection with the comutator. Take the vac to your Aerus/Electrolux dealer/shop for repair.
Joe

The motor may have a sticking brush or a dead commutator segment. Turn off power to the unit to check for sticking brushes. Reapply power, does it now run? If not, shut it off, physically turn the motor a few degrees, and reapply power. If it still doesn't run, look for loose wiring around the motor. If it does run, replace the motor armature or the entire motor if the armature is not available as a separate part.

Detach the vac itself from low voltage thin wiring leading to the house. With the vac plugged into power, try the manual switch and then try shorting across the low voltage exterior terminals with a rubber gripped set of pliers.
If you can hear a clicking inside, this is the vac's relay trying to start the motor. If the vac is more than 5 years old , or used more than 2 hours a week, you may need new carbon brushes, or a motor overhaul or replacement depending on wear. Carbon brushes are specific to the motor model # inside the vac, most often an AMTEK Lamb motor.
If you need brushes, the motors comutator should also be inspected for excess,wear, like gap ing between its conatct segments and "apple core" shaped wear
.
You you have a meter and can test for continuity across the motor leads, do so and post back.

If you don't have a meter, you will likely want to lift the vac off the wall after these checks and take to a repair shop, saving $$$$ for a house call...

Is there a small LED light illuminated where the low voltage wires connect to the main unit? There may be a small rubber boot covering the connection and the light. Just slide it back, and there should be a green LED light if the unit has power. If the LED is not on, there is no power to the unit (tripped breaker, plug came loose from electrical outlet, etc.) If LED is illuminated, short across the pins where the low voltage wires connect to the main unit. (These will be small 18-22 gauge wires, not the larger electrical cable!) You can do this with a coin. (Don't worry, it's just 24 volts and you won't even feel it) The unit should come on. If it doesn't, and you have light from the LED, then it's probably the relay on the board inside the unit, or the motor. Good Luck!