This is a little guide for to calibrate your screen at sturt up when your touchscreen is not calibrate and you can't access to sub menu of gps for to calibrate it. It's for becker system and also for igo primo based system. I think that it is possible use in others systems with some changes. In attachment there are two folders and a sys file. In relation to your navigation system you can use version 1 or version 2. First look inside your folder for understand which version is for you. Just copy directory and file in the same place into your gps and copy a string into your sys file.
Very thanks to official supplier COSTAS3850