What I was told was that Topre uses something like M2*4 screws, so I bought a small kit of varying sizes but after a first mistake where I didn't double check the screw specifications, I got some that were pointy and with larger spaced apart threadings, these were not suitable for the Topre threadings since the screws actually need to be tightly threaded and have flat ends. So I got another kit which had those kind of screws. What seemed to work great were the M2*6 screws as they were long enough to go all the way in.
And here was the kit I bought: https://www.amazon.co.uk/gp/product/B07 ... UTF8&psc=1
In hindsight I probably could have gotten some with rounder heads similar to the original screws, but these seemed to work well enough.
Hope this helps.