Did these problems just suddenly appear, or did something happen?
Your toolchange problem sounds like maybe the ATC macro got deleted from the memory.
Check parameters 230 to 239. These set the M-code that call macro programs O9020 to O9029. One of them should have a 6 in it. So if parameter 230 has a 6 in it, M06 calls macro O9020. That program must be in memory or you'll get alarm 078 when you try to execute an M06.