How do I access the gear box? - KitchenAid KSM150PS Artisan Series Stand Mixer

Contact Robot Coupe direct with a view to having it replaced under warranty.

https://www.robot-coupe.com/usa/en_US/contact

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It is more than likely in the planetary or the fuse gear inside the gear box. Try it once you have the planetary off before you go looking inside the gear box. Easiest is planetary problem but far far more likely is the fuse gear.

There should be an access screw on the bottom of the transmission housing where grease can be checked or introduces. Remove this plug and carefully introduce a tool such as a wide flat screwdriver to 'lock' the gears from turning. The nylon gear and 'isolator' should come off fairly easily

pack it full the grease seems to find a way to move a way from the gears after a while so you new grease and pack it in

Here is the exploded parts list fr a K45, perhaps it will help him:

http://shared.whirlpoolcorp.com/assets/pdfs/literature/Repair%20Part%20List%20-%208212369.pdf

Check that the gear on the shaft that the clutch gear engages with does nort have a sheared key.

I would say without looking at it a key is sheared or gear teeth are worn on the gear.usually its a sheared key,however if the mixer is older they use a dive key assembly which you would have to replace the shaft.I'm a hobart tech and repair these mixers often,any ? let me know.What is the ml # on the data plate?

This kind of unit are lubricated with grase paste. If the unit stays inactive for a long time, or if the motor and gears are overheating the grease paste gets melted into thin oil, and that will cause the leak.
The oil leak is usually coming from the gear box inside the appliance.
To fix the problem the unit must be taken apart, and cleaned. After this step, there is need to spread again the grease, using special foodsafe grease paste.
Disassemblying the gear box is not that easy, you will need previous experience and a gear puller to do the job properly and safely.
This appliances are also held with security screws to prevent the users from taking apart the unit, and can only be disassembled using a Security screwdriver tip.

The grease can be purchased here, check at the bottom of the page: Kenwood chef food mixer Grease.

Very close; stand mixer parts (included accessories and manual only) can be accessed from this page:
http://www.wpcookware.com/categories.asp?cat=32
Just select your mixer's part number (located on a sticker inside the base) and click the link for a list of available parts. You will have to create an account to see anything useful, but all they ask for is your name, a password and an email address. When adding items to your shopping cart, be sure to check the 'Select Item' box. The ordering page will ask for the usual info. Prices are reasonable, but beware the shipping cost!