Replace oster kitchen center base drive par...

I'am the guy who posted the comment I found out how to do this.
There are 2 possible solutions the 2nd is not pretty, hope the first works for you it didn't for me.

1- The motor must be lock up, by placing a thin screwdriver through the holes in the base into the fan down into the motor,holding the screwdriver, remove the square drive from the top.The part you are trying to remove actually is screwed into a gear in the gear box, you will need a spanner wrench,(sometimes a strong pair of long nose pliers will work, engage the spanner holes,hold the screwdriver ,and try to unsrew it, you may need someone to hold the screwdriver,because it takes a lot of force to loosen it.These are regular threads,and unscew counter clockwise.

2- if #1 doesn't work-this will- but its not so pretty.The motor assembly attached to the gear box will have to be removed,it will come out as one piece
Remove the bottom plate,unplug the white wire from the speed control,and the blue- white wire from the board,also you will have to remove one of the brushes with the white -blk lead.
Now you will have to actually break off of the top plastic(bakelite)by whatever means you dream up (I actually used a small wood chisel to score a line, and crack it) once its cracked, it breaks apart easily.Once thats done turn it over and remove the four screws holding the gear box to the housing you will now be able to remove the gear-box motor assembly.
Remove the 3 screws from the top of the gear box pry the box open,remove the gear with the piece that needs to be replaced,now you need to get the piece unscrewed from the gear.I did this by locking the nurled end into a vise, and very carefully grabing the gear teeth with large channel locks(if you think of a better way thats great)it work for me,but I was very concerned about the gear teeth,you can't slip.
Try the new piece to make sure it sets all the way down to the bottom of the gear(it must or your head will be to high ,and won't lock down)if all is well,make sure everything is greased,and start re-assembly, the new coupler ,and the square drive will be the last 2 pieces assembled from the top, once again locking the motor with a small screwdriver.