Hameg Hm305 problem

[carlos2020]

Hi
i´ve one oscilloscope hm305 and it have a problem in y position, i cant go to negative part of the screen, and i think that is a problem of a capacitor in xy board, but i cant find schematics for this board and i need to confirm the value of it

could someone give me the schematics for this model? or have that model to let me know the value of it?

regards