Square drive pin for Osterizer blenders?

I simply slid a small screwdriver in through one of the holes under the base to prevent the fan from spinning and unscrewed the pin counterclockwise using some small channel lock pliers. No disassembly necessary.

I can't find a service manual anywhere on the internet, but I can try and talk through the steps I followed to replace the square drive pin and rubber coupler for my Osterizer. It's a bit tricky.

In my case, I sheared the rubber coupler that attaches to the square drive pin (by blending a spoon, of course), so I could just take the square drive pin off the top, leaving me with half the rubber coupler inside the blender housing and out of reach.

When you remove the base of the blender (using a 1/4" socket wrench or nut driver inside the four rubber feet), you should see the big metal fan covering a big motor assembly. The fan is screwed on one side of the motor shaft, the rubber coupler and drive pin onto the other. How much of the motor assembly you have to take apart depends on how much of the drive pin / rubber coupler is left.

Looking at the top of the unit again, try to get a pair of Vise-Grips clamped solidly to the rubber coupler (or what's left of it). If your vise-grips are too chunky to reach inside the blender housing, you'll have to do more dissassembly.

Get a 4" extension attachment for your 1/4" socket wrench. Look deep inside the blender, and you'll see four bolts holding the motor onto the housing. They should be slathered in grease. Being sure not to lose any washers, rubber gaskets, or other parts, Unscrew all four bolts and slide the motor assembly out of the housing.

Now you can see both ends of the motor - the drive end and the fan end. Clamp the motor's square solid magnet frame into a vise, so you can work freely. Take the fan off - notice that the threads have a flat spot ground onto them to keep the fan aligned. VERY CAREFULLY clamp a vise-grip onto the flat part of the fan-side motor shaft, using a thin piece of wood, folded rag, etc. to protect the threads on the non-flat side. Get this good and tight, but don't dent the threads.

Now, clamp another pair of vise-grips onto what's left of the drive pin/rubber coupler, and spin counterclockwise to loosen. Done!

I haven't reassembled mine, but I can tell it'll be tricky to mount the motor back into the housing again. Good luck!

Check http://manualfox.com - they claim to have found service manuals for SUNBEAM products.