Keith,

Can I ask if YOU can help those that might be able to help you. There are many flavours of 6040 machines, some information about the VFD, spindle, control system and the CAM software that you're running? Once people understand these, they might be in a position to help.

For info, I don't have a 6040 and am unlikely to be able to offer help beyond the above advice.

Kind regards.