stop spinnig with a bit of force

hi all,

I have a kitchenAid that after repair return seems to work fine when the bowl is empty, however as soon as I put something inside it even the smallest amount it will stop spinning while the motor keeps going. It sound like some gear tear or slack somewhere but opening it up all seems to be good and fine (can't check the slack the motor gear and the nylon gear). Of course I tried to go back to the guy to fix it and every time he fix it it hold for one use!

Any ideas? let me know if you want me to provide some pictures