Thank-you very much ScottyUK and Parchie for your help.
seems like you were both 100% correct. my mill now has two electrical speed settings.
Just need to install the switch and i can close it up for another 10 years.
I have a Maskinner milling machine.
It has a two speed switch.
It operates on 3 phase 380 volt.
It was working well. then the switch started to drop a phase.
If i re-switched the switch it would make contact and run perfectly again.
I decided to replace the switch before the motor became...