Seized cutter My cutter is seized to the shaft. Any ideas how to get it loose?

It's like a suction is created. I have had this happen. I managed to get mine off with a blunt knife to give a bit of leverage (not ideal I know to put a knife near an expensive piece of equipment but it worked for me) Once you have the blade cutter off I suggest oiling the metal prong that it sits on with something like vegetable oil or olive fairly regularly to avoid this happening again.

Do not use WD40. Wear heavy leather work gloves. Lightly tap two flathead screwdrivers positioned opposite each other to initially pry the blade apart from the main body of the juicer. Alternate tapping on the screwdrivers until some of the shaft is exposed. Tilt the juicer towards the blade and drizzle olive oil on to the exposed shaft. Every few hours return juicer to stable upright position and use a hammer to lightly tap a screwdriver positioned at an angle that will not gouge the shaft. Rotate blade manually and tap in different positions. Keep juicer tilted towards blade in between tapping attempts to allow oil to penetrate shaft opening. Continue drizzling olive oil on shaft as it is exposed. Cutter may need replacement after this procedure. Use steel wool to thoroughly clean shaft. Soak Cutter blade in hot soapy water for two days.

Not familiar with the brand name

First, check to see if there is a set screw in the side of the cutter which screws against the shaft.

If no set screw, a gear puller would probably do the trick. There are many types -- you might luck out and find one which will fit on your first shopping trip.

I've been using my Champion for about 20 years, and have always used a very thin coat of olive oil on the turn shaft before sliding the cutter on. I've also used it before I've used the grain mill, and it has been fine.
If I were you, I think I would get out as much Crisco as I could with a chopstick (or something similar), put in some liquid soap, and some hot water. I would think that would loosen anything that was compressed or stuck. It might take a few times, but that's what I would try....or you could order a new cutter from Champion. I've had to order parts from them in the past, and they have been great.
Hope this helps.....

Soak it in Hydrogen Peroxide or vinegar.

The manual that came with my juicer suggested putting a drop of cooking oil on the shaft to lubricate it before putting the cutter on. That works well for me.

This is a response I received from Champion Juicer- I am amazed at how fast they responded. His solution is below- Hello Cathy

To remove the cutter from the Champion Juicer motor shaft, take two small
screwdrivers and place them between the back side of the cutter and the
stainless steel portion of the hub. Apply pressure on the screwdrivers and
the cutter should begin to slide forward. When driving the screwdrivers in,
make sure they are spaced far enough apart so they don't damage the motor
shaft which is located in the center of the cutter. If the cutter does not
come off, leave the screwdrivers in place and insert something under the
rear of the Champion Juicer (like a book) to elevate the rear of the
machine, thus allowing the cutter to tilt forward. Apply penetrating oil
between the screwdrivers. Because the cutter is now angles forward the oil
will run inside the cutter. If this is done for several days the cutter will
come off by applying more pressure to the screwdrivers. By merely pulling on
the screwdrivers you will have to use a plastic hammer and slowly tap on
each of the screwdrivers until the cutter breaks free. Tap one screwdriver,
and when it is snug, tap on the other screwdriver until the cutter breaks
free. When this is done there will always be one screwdriver coming loose
and falling out of the slot. Do not rush the removal process; give the oil a
chance to work. It is possible the hub and cutter will be damaged during the
removal process. Contact us for current replacement prices. Once the cutter
has been removed you should polish the motor shaft to remove any film or
burrs which may have developed. If you contact us with your address we will
mail you a piece of fine emory cloth to polish the motor shaft  at no
charge. You should always apply a slight film of olive oil on the motor
shaft to prevent sticking of the cutter. Do not use other oils, as they tend
to break down from the heat during operation of the juicer. If you wish to
speak to a repair person, please call our company weekdays @ 209-369-2154
between 8:30 a.m. and 4:30 p.m. Pacific Standard Time. We would be happy to
offer any assistance you may need.

Thank you
Carl