I purchased a rebuilt/like new motor for my jeep. Had it professionally installed. Motor has a loud, terrible knock. The buyer is asking the mechanic who did the install to diagnose the problem before issuing a warranty claim (sell page says this is a covered issue). Return period is past but seller advertises warranty covering problems like this, but so far has not offered a specific plan to fix this motor or get me a functioning motor.
What recourse do I have with the seller?