Wiring of flashers and 153IR is not affected. The "buck converter" is spliced into the 2 wires going to the bell module.
If you are willing to wait for free shipping from Asia, above shows one for $3,
But as asked earlier does your bell work at all?
RickO described a behavior where the bell stops working from overheating after it runs for a while in this OGR thread. MSRP for the MTH 30-11014 is $70 which includes the flashers. It's not clear if you can buy JUST the bell module. There are other crossing bell sound modules if you can't buy the MTH bell separately at a reasonable cost. By reasonable, I'd say no more than $25 for a plug-and-play module. If you're a DIY'er with time on your hands, there have been OGR discussions on making a bell module for around $5 using an MP3 sound module.
If you don't have a handy source of a lower voltage, momentarily attach the 2 wires from the bell module to a 9V battery (either polarity OK) to see if it comes to life.
