First thing is I would verify the programming is correct (PL tone too). And all radios set for either wide or narrow and not a mix. Also I would check the PL deviation and TX power. Also for physical damage (broken antennas or bent contacts).
Granted, I know you are just an end user, but a shop should start with the above.
One thing you can try, do the radios have a monitor button that opens the squelch? If so, press that while the other user is talking and see if you hear them then.
My boss put in for another service call for some time next week. Someone is going to come out and take some real time during our slow period to see what is going on. If they manage to find a fix then fantastic, it will have saved the company money and I will only be out 100 bucks (And with a better radio IMO).
Can someone explain to me how a cloning process works? Is the Kenwood attached to the Motorola somehow and then that is how programming is transfered over? Or is it just more or less jotting down what the programed channels are on the Kenwood and then plugging them into the Motorola via its own software?
This is all so fascinating. I never thought there was so much involved when it came to 2 way radios. What a neat hobby.