I have a Sunshine Yellow Kitchenaid professional 6, 525 watts with three mixing attachments, and pouring shield, in mint condition, just had it in the repair shop to replace the plastic seal (not sure if...
Hi Lisa. Your mixer's plastic transmission housing failed when you were mixing bread dough or cookie dough. When this cheap plastic part fails, it can cause internal damage to the worm gear shaft, worm gear bearings and their seats as well as other internal damage. This kind of damage is not easily found, as the grease inside the transmission must be removed and parts cleaned to fully acertain damage. If the trans. housing was the only part replaced, I would view the repair as only partial.
If the mixer now runs well, without any internal noises during operation, consider yourself fortunate. You could advertise that you have upgraded the mixer (metal housing). A price between $200.00 to $250.00 would be in the ballpark.
If this solution has assisted you, please rate it. Good luck! ricardok45