It might be a good idea to check your mains voltage. The machine was designed for a 230v input voltage, so any circuit in the game that is supplied by an unregulated voltage (such as coils and lamps) could behave in undesirable ways when supplied with over/undervoltage (even if the difference is just a few volts). I know at least in the USA that the average mains voltage has crept up over the decades from 115v to as much as 125v in some locations, and this actually has caused some issues with vintage electronics (especially tube equipment).

If something similar is happening at your location your coils may be getting a little too much voltage, which will of course make them fire with more force. I would probably try to fix this first by substituting a coil with slightly higher resistance (you could also add some additional turns of wire to the existing coil, which would be a somewhat tedious job but would allow you to fine-tune it to your specific game and mains supply).