Hello, I have a shopsabre 7214 with 7.5 hp spindle controled by Variable Frequency by PC, recentley I have been expirence 2 issues:

1.- Even the spindle comes to turns off, the screen of the Variable Frequency still showing high levels of hz and still running and never comes to 0.0, fluctuate between (350 and 450 hz)

2.- One of my servo motor Mitsubishi which move "Y" axis, suddenly stars making noise like roar increassing it and its timming belt is fluctuating

I am not electronic man but want to know how I can fixed

Thank you