Possibly locate a polish national? My limited understanding of any pop testers function is to take injector up to spray or release pressure and observe pressure gauge for point of fuel release. Next observation is to study spray pattern for uniformity. Watching for any leakage prior to the injectors release pressure as well. The instructions may contain some information on modification of injector release point by changing internal shims. This may not be the information you are looking for though. If I am wrong I do not mind someone correcting me. Importance of keeping tester clean internally and using really clean fuel to avoid getting dirt into injectors under test probably is stressed as well.