7770 Lecrostop Radial arm saw not starting

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Hi

I recently got a 7770 radial arm saw, but have been unable to use it.

each time i turn it on the blade starts turning and it trips the power.

If i start it without a bade attached it runs fine. as soon as i fit a blade it trips the power again.

any thoughts, might it be the starting relay or  a issue with the dual voltage motor.

I have measured the voltage in my workshop, 230V and the breaker that trips is a 20A breaker.