Question regarding KitchAid mixer, Model K45ss. excessive noise.

The fuse gear may have failed, if it has your beater will also not drive properly. I'm not familiar with a grater on your model.

a gear or gears. their usually plastic and will damage before the drive shaft

it could be. also a tight bearing/shaft could be culprit. sometimes, the two nuts that hold the motor field loosen; and even fall off.

Firstly I would take the head apart to find out what has failed. The oil you see should be a thick grease. Normally it is thick enough not to leak in this way. Has it been repaired and the wrong grease used? If it is making a funny noise it could be that one of the gears has failed. Most parts are easily available. Have a look at the parts list at:
http://shared.whirlpoolcorp.com/assets/pdfs/literature/Repair%20Part%20List%20-%208212369.pdf

brooksite, Sorry to hear you mixer is making a lot of noise... They shouldn't do that. Do you still have the K45SS Parts List? If not, you can download a PDF version from the KA website. Click on Customer Care>Locate Manuals & Guides> Enter the 6 character model number (in your case, use K45SSW select Parts List (1) and then check to see it this matches your mixer). You can check on page 4 & 5 for the disassembly and reassembly of your mixer, along with all the parts. It will be messy but gratifying. Once apart you can check for any other unseemly wear and tear on the gears, etc. You may find that it's just one particular gear that's causing the noise.
As far as parts go, here are four potential vendors in no particular order: RepairClinic.com; mendingshed.com; searspartsdirect.com; partstore.com (this vendor had the best prices for my wife mixer's parts, but sadly they had to back order them, which was disappointing to SWMBO). Prices for the same part vary widely between vendors, so do your comparison shopping. Also, here's a link to a site that details the disassembly and replacement of a mixer's grease, which might be helpful, too. http://www.foodonthefood.com/food_on_the_food/2009/04/how-to-repair-a-kitchenaid-mixer-yourself.html
Good luck and have fun. I hope this helps. Howard, Burke, VA

Yes this indeed does sound like you have a problem. There could be a couple different cause of this noise. If your main drive or worm gear has been damaged, it is likely to not run at all or jam up. So i think this is not the problem. There is however a codder pin located inside the transmission gears this can be seen by removing the upper housing of the unit, and then exposing the oil and gears. clear away the oil surrounding the gears, and save this grease for later. After this you should be able to visually see this codder pin AND the gears, rotate the gears while inspecting them and the pin. If the pin is slightly bent or broken this will make the grinding noise that your are talking about, while still operating and driving the unit. part number for the codder pin is 9705444. If however the noise is coming from the motor area this could indicate a worn or faulty motor bearing. This can cause the motor to operate on an angle and can cause a rubbing noise from the cooling fan or the winding of the motor itself rubbing on the mixer housing. Part number for the braket and bearing is 3180526. both are relatively cheap and easy to replace. If you find and fix the problem be sure to inspect or change the oil as this can often have metal chunks and other particles. Hope this Helps

Thanks

I push down with kniffe the chrome ring and remove the agitator shaft that was broken

If it is the worm gear then the planetary will stop turning when there is a load on the paddle but the motor will continue to run at the speed you set it at. I'd be checking the carbon brushes, checking that the field assembly has not loosened up a bit and then I would see if the speed control plate adjustment screws are loose. I'd then reset the speed and see if it stays as it should be.

If you have some length on the brushes they sound OK. If they're getting short they may need replacing because they're not making full contact all the time and may be arching. Your problem may also be in the gearbox. May need new grease and have the gears, shafts and bearings checked for excessive wear.

take off the chrome ring around the rotator. remove the screws that were hiding under it. pull off the rotator and replace the "O" ring on the shaft.