Need help !(Hameg 504 scope sweep line not in the middle)

[cnqhdszq]

I bought a 2 hand Hameg 504 scope .
At the begining ,the powersupply unit does not work.After 3 day's work .it works fine  now  . but when I pressed "AUTOSET " the trace line is not in the middle ，it is deviation to left  of centre. I must  move it by the "X-POS" knob ,When I press "AUTOSET "again ,the trace move to the left again.
When I open the "MANUAL ADJUSTMENT MENU" and select the "SWEEP GENERATIOR" it says"PRESS SECURITY KEY !"
What should I do next ? .

[aqibi2000]

That is a nice scope!

[coromonadalix]

User manual  if it helps

https://cdn.rohde-schwarz.com/hameg-archive/HM504-2_english.pdf

https://elektrotanya.com/hameg_hm504_oscilloscope_deutsch_um.pdf/download.html

[cnqhdszq]

thanks !!