My Miyano LS18C (new 1993) screw machine will not rotate spindle forward or in reverse below 525 RPM. The machine is rated 400-8000 RPM. Above 525 RPM, the machine works as if there are no problems. There is no gearbox on the spindle and no %speed override dial on the operator's panel. Spindle will orientate correctly and somehow during orientation process low RPM are available. No alarm of any kind is displayed when RPM below 525 are commanded. The block is executed and the spindle is not rotating. Backup battery was always good, so the parameters were never lost. That was yesterday.

Today, the machine spindle will not accelerate or come to a stop as quickly as it used to. It just takes its time to get up to speed and it actually will not reach the programmed speed, so when 1000 RPM is commanded, it will only get to ~700.

Has anyone had any similar problems? Does anyone have any ideas to what this may be?

Model: Miyano LS18C
Serial: LS18011C
Controller: Fanuc 18T

It works with a FUJI drive and motor on the spindle. FUJI drive type: FRN003M3-21