I currently have a block grid cutter (a cheaper variety than the one you sell, made of wood and recycled plastic) and the wires break fairly often which is time consuming to replace, sometimes even ruining some of the soap in the process. I’m not sure the reason, but I need to know of the probability of broken wires happening with your unit as well.
I don’t know the gauge or type of the wire you use. Ours is a special grade that as far as I know only one company in the World makes. We have sold over a thousand cutters over the course of 12 years and seldom need to send replacement wire to anyone.
Sometimes it is not the wire but the wire tying method. We designed our wire bolts to work with the particular wire we use and to pull the wire, straight on. They are also designed to allow tiny adjustments in the tension and to lock firmly in place.