The chosen solution was simple.
Since on the picture the third line was OK, I added 2 empty lines above.
And below was due to calling empty lines in lowres out of sync.
Solution there: fill the screen in highres with a lot of delay.
I needed a few bytes for the solution, but I knew of a few bytesavings in a routine.
And the ZX-pand load????
I altered also some system variables.