error 740 RIGID TAP ALARM

Good evening. I have a Mori Seiki nh5000 which gives me error 740 RIGID TAP ALARM. Random gets this error. For example, the machine can work 5 hours or a day with the same details, or even 1 day and then goes into alarm. Reset, starts and after a certain time goes into alarm. Given that, a few days before, the switch of the 220v transformer occasionally jumped, turning off the machine. This for almost 1 week. I changed the switch of the transformer because I thought of an incorrect voltage.
In order of facts:
1. A week ago everything ok.
2. After that, the transformer switch jumped.
3. The first 740 RIGID TAP ALARM errors appeared.
4. The switch of the 220v transformer has been changed.
5. 740 RIGID TAP ALARM errors always occur every now and then (at random).
Anyone have any ideas?
Thank you.