Transaxles are "built" by assembly line workersOne would think the mechanic who put the transaxle together would have noticed such a flaw.
Transaxles are "repaired" by mechanics
Not sure the former has time to scrutinize the surface treatment of all parts prior to install
At times it takes even a good mechanic a while to i.d. a problem.
I wouldn`t be happy about it either but, these things do happen