My sxs does not care pretty much, nor did the telco when we had that service, so I did believe this was not an critical issue, everything between 50 and 70 % break has been ok. I have had some issues with my D.I.Y. trunk unit, and has not seen the relation to this.
Earlier this week I understood something, my Cobra made for Oslo has pretty accurate 60% break, and my Danish D2 has 67%, the last did not dial out on the trunk line. All my US phones dial out, some of my European phones does.
Today I did a rough adjustment on one and got the break ratio to 56%, and now it works.
I guess I leave it there until later, and adjust it if needed. Bending springs forth and back to much are no good idea.
What are your experiences about make-break ratios?
On the old Strowger switch too low,no step, to high drop outs
Many decades ago when I worked for US Robotics, the big modem manufacturer, their modems had an "S register" to set that, and I believe that the choices were something like "US" and "UK". At the time, I had no idea what that meant, so I asked one of the engineers and was told that the phone switches in north America and Europe handled pulse dialing differently with different make/break (I think they called it something else) ratios, so their modems could be set to do either.
Here in the UK the make break ratio can be critical with some ATAs. I use a Grandstream 502 and found that some of my UK phones would not dial out reliably. Some refused to dial at all. Then I was told to close uo the dial make/break contacts just a little. This has the effect of breaking the contact later and re_making it a little earlier. Thid has totally solved the issue for me.
I think the problem is the acceptable ranges for the US and UK ratios cross over. At one end of the range you are ok on both systems, but not at the other.
I've also found some of my Tele 782 (UK 700 series DTMF phones) are out of spec on the PSTN but my Panasonic KX-T is okay with them.
Panasonic must have made the most tolerant PABX ever.