I agree with the fine gents below. Although Ive been retired for years as an electrical design engineer, when I specified magnetic motor starters they were available in different hold in coil voltages (both low and high voltage)REGARDLESS of the voltage of the motor. Therefore perhaps the voltage now being applied to the coil is too low to engage the relay so see if you can replace the coil in your starter ????? with a 230 volt (if thats where youre now operating).
Similar the thermal overloads (heaters as they are called) need to be sized to protect the motor so if youre now operating at 230 versus 460 volts they also need to be changed and they should be readily available in the new current rating your motor requires.
The starter relay contacts (NOT talking about the hold in coil now but the actual high current contactor) have a certain HP and current rating, so since you have increased the current by operating at a lower voltage just be sure the starter is suitable.
I always specified a lockable either fused disconenct (safety switch) in sight and within 50 feet of a compressor if a seperate magnetic starter was used or else a combination starter and, of course, flex conduit for the final motor connection.
John T NO WARRANTY its been toooooo long since I did this as a profession and Im rusty on the latest codes