How do I get the remaining beater to release and come out?

Try to wiggle it out with the button pressed.

Get a copy of the Repair Part List for your model at Kitchenaid.com
Constant pushing of the beater onto the Agitator shaft (40) can cause
it to be pushed in too far into the Planetary (33). With the beater in place,
use a rubber mallet to slightly tap the edges of the beater and push the
shaft out until you can see the retaining clip.
Now you have enough clearance on the shaft to push the beater upward
and twist it to remove it.

Get a copy of the Repair Part List for your model at Kitchenaid.com
Constant pushing of the beater onto the Agitator shaft (40) can cause
it to be pushed in too far into the Planetary (33). With the beater in place,
use a rubber mallet to slightly tap the edges of the beater and push the
shaft out until you can see the retaining clip.
Now you have enough clearance on the shaft to push the beater upward
and twist it to remove it.

Get a copy of the Repair Part List for your model at Kitchenaid.com
Download the following Kitchenaid Service Manual:
http://www.kitchenaidparts.be/centers/servicemanual/mixer.pdf

It covers several models including yours.
1. Check/Adjust the Flat Beater to Bowl Clearance:

Turn screw (A) SLIGHTLY counter clockwise (left) to raise the flat

beater or clockwise (right) to lower the flat beater
2. Check the Beater Shaft (Agitator Shaft) making sure the Retaining ring
is flushed with the surface of the Planetary Assembly
Constant Pulling and Removal of the beaters can cause the Agitator shaft to move
3. If the above two still don't solve your problem, follow the service manual
directions to disassemble the Planetary Assembly and check for loose screws

Put a few drops of cooking oil in the holes the the beaters are inserted inMake sure to unplug the unit. Pushing the button, work the beaters pulling lightly. Good Luck

The beater is held in place by a pin and spring arrangement. Lift and twist the beater. If that doesn't work, the pin is trying to come out...and is wedging against the beater. Tap the pin back in a bit, and the beater should release.
Regards, --W/D--

Go to sunbeam.com, select "kitchen", then select "customer service", then "instruction manual", then "stand mixers", scroll down to model #

The mixer is not designed to be disassembled or serviced. When it breaks (and it will) Sunbeam will replace it under warranty if you are lucky or you toss it in the trash.

That said, start by prying out the beater release button. There are two small screws under it and one between the beater inserts to remove the chrome front cover. The large black dial at the rear can be pulled straight off, revealing more screws. The motor and drive assembly in the top cannot be removed without disconnecting wiring from the circuit board in the base.

Okay, we just figured this out ourselves.
There is a little hole on the neck of the mixer, where the mixer motor meets the neck. While pushing the tilt release button, stick a small screwdriver into the hole (it will not go far) and pry the latch upward. While holding the latch up and the tilt button, have someone pull up on the motor while holding down the base. It might take a little muscle, but after that, the motor will be able to tilt back and forth like it did before it got stuck. If you are the one holding the tilt button and latch, please wach your finger so they don't get pinched when the motor swings up.

Look under the mixing head on the bowl side. There's a square "tab" that looks like the one on the back side of the machine. Pull it towards the bowl to release the mixer head from the base.