As long as the new one is 240v you should be fine, theres also a 480v version, make sure you get the right one. The new style should work the same way as original even though they look different. 250v is on the high side. Have you been using it a while or is it a new installation? Id say your close to the edge. These suppressors are metal oxide varistors. Once voltage gets above a certain level they conduct power to ground to protect the rest of the machine from over voltage spikes. Over time the voltage level that they start to conduct can drop lower and lower until you get to a point where it starts to conduct the normal line voltage and then they blow up.
I had one go on my spindle braking unit. I just cleaned up the board with alcohol and soldered in a new one and its been fine ever since. I did re tap my transformer 10v higher to drop the voltage at the VFD just to be sure. This wont help in your case as the suppressor is before the transformer. That doesnt really make a whole lot of sense really, whats the point of having a multi tap transformer if the suppressor cant handle higher voltage?? If the new one blows up you might need a buck/boost transformer to drop voltage.