I am not a mechanic
and guess it's possible to crack a case from installation
but cannot imagine how. Maybe a mechanical expert will chime in on that subject.
I would be very tempted to lean on ZF. What did your service
department say was the cause? Are they an independent repair shop or a ZF dealer? Do you know and trust them?
If your mechanic
thinks it's BS I would go after ZF. You can sue them in small claims court with no lawyer and very little cost. I had a hassle with Royal Caribbean Cruise
lines once. They lost
my luggage and more or less blew me off for a couple of months, ignored multiple phone
calls, voice mails, faxes and emails. Finally I sent an email
copied to every name and office I could find at RCC informing them that I was suing them in the local small claims court. I had a check in three days.