The lever to start the machine the one that moves to the right to select the speeds won't move

Question edited for clarity.
Question moved to category.

The speed lever is electronic. Videos and the part in the link.

https://www.google.com/search?q=Kitchenaid+Professional+6+mixer+speed+lever+stuck

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The starting position for those top speed control plate screws with the lock nuts it 8 full turns in when you fit the plate. Correct adjustment begins in or out from that point. The bottom screw should have been left where it was to start with as that is for adjusting the start position so that when the lever closes the switch contacts to start the mixer the plate only starts moving when the lever moves to the second click. Try and get the bottom one roughly right and then work on the top ones. Turn it to the first click on the speed lever and then EVENLY adjust the 2 top screws to have the planetary turn 13 to 15 times per 15 seconds. Lock up the lock nuts and then check that the bottom screw is in the correct position with speed increasing a small amount as the lever slips into the second click.

Same as on my N50. Perfectly normal,

Ideally you need to fix what's bent and that normally would involve splitting the cases to get at and repair or change the speed control lever. If you don't want to do that then removing the back cover and altering the adjustments and maybe bending the switch contacts may make it operate at both ends of the speed control.

The spring attached to the speed control switch has come off or broken. Does the switch stay in one place when you move it or does the switch move about freely. I need a little more info to be more help.

Get A Copy of the Repair Parts List from Kitchenaid.com
Make sure the Speed Lever and and the Speed Link are in place
and operating smoothly. The two Large black screws you are referring to
are the Motor Brushes Caps. The Carbon Brushes are keyed and
designed to be inserted into the Motor Housing but one way. If you
insert them in wrong, they will not make contact with the Motor Coils
and you mixer will never run.

All you have to do now is adjust the mixer speeds (if necessary):

Remove the screw holding the End Cover and locate the three screws from the Control Plate.
All three (2 top left and right, and 1 bottom) must be adjusted.

1. Loosen the lock nuts enough & Turn the 2 top screws clockwise until they cannot be turned
anymore. Leave the bottom screw alone for now.
2. Use a dab of white paint or paper whiteout to mark the positions of the Phillips screws.
3. Plug in your mixer and Set the speed selector to "Stir".
4. Turn each top screw One full turn couterclockwise (alternating between Left and Right)
Keep making one full turn at the time (for both left and right) until the motor starts running.
5. Put your hand near the Agitator shaft and allow it to brush your finger slightly. Use your
watch or clock and start counting the number of times the shaft touches your finger in
60 seconds. The correct count should be 60 RPM (Rounds Per Minute). If it is less
or more than 60, give each screw 1/4 turn counterclockwise or clockwise and start counting
again. Now tighten both lock nuts.
6. Set the speed selector to "6" and turn the bottom screw either clockwise or counterclockwise
to achieve a speed of 180 RPM.

For your reference, the planetary RPM's for the 5-qt. tilt-head Artisan Stand Mixer are as follows:
Stir speed - 60
Speed 2 - 95
Speed 4 - 135
Speed 6 - 180
Speed 8 - 225
Speed 10 - 280

Open up the Motor Housing and inspect the Switch Lever with Stud.
The Lower Gearcase has many depressions which allow the stud to
snap into it when the Speed Selection lever is moved. If the Stud
is worn out then there isn't much you can do but replacing it.
3184193 is the Switch Lever And Stud part number for your model.

The Speed Control lever is linked to the Speed Link mechanism, which in turn moves the
Speed Control Assembly to allow the motor to operate at different speeds.
Get a Repair Part List from Kitchenaid.com for your particular model to see how it works.
As you select different speed setting, the Speed Link simply moves forward or backward,
thus pushing the Speed Control Assembly back and forth.
If you cannot move the Speed Control lever, means that the Speed Link is somehow bent
or out of place. Remove the Motor Housing and the End Cover and check it out.

Look under base for any gearing. Usually the momentum of the beaters will turn the bowl.

does the motor still run or does it slowly start to get less loud? or is the beater assembly that dosnt work? two different issues. if the motor runs but dosnt beat then its the planitary gears that are ground out and need replacing. if the motor slowly dies out then you need to replace the motor.