Many of the tuning problems with the KHF-950 are related to improper antenna installation. Here are a few possibilities:
Poor connection on antenna feed thru.
Long wire broken (a wire can crack and not be visible because of the thick insulation)
For a short antenna run where the termination point is grounded, the ground may have become disconnected
The wire from the KAC-952 coupler to the antenna should only be 6 inches ideally. A length of 18 inches is the absolute maximum. If the antenna feedline is longer than this, the efficiency of the KAC-952 will be greatly reduced possibly causing tuning failures at certain frequencies.
In some cases, the KTR-953 could be at fault but not likely in most cases. If the tune cycle starts, then the KTR is providing ample power to the KAC. If the tune cycle never starts and the system immediately goes into tune faulty (beeping tone in headset) when the PTT is activated, then the KTR most likely is faulty.