Can someone give me advice, when running my spindle at 500rpm when I stop the spindle with M5 it still runs at 15rpm however at 800rpm I stop the spindle and it stops, go back to 500rpm and stop the spindle it creeps at 15rpm. I've had this for years and thought it was electronic interference but feel it might be something to do with my initial setting as checking the RPM with a strobe 500rpm gives 400rpm but at 800 rpm it gives me 800rpm. Any advice would be welcome as the only way to change the tools is to change the low revs programs to over 800rpm and introduce a tool change them put speed back to 500