Tektronix 2432 with vertical failure?

[weakbit]

Hello,
the failure is if i turn the time base A to 50us/div the horizontal line (beam) can never adjust vertical.
If the time base is turned to 100us/div the beam (horizontal line) is normal and the oscilloscope is working normal.
From 50us/div and under the vertical disturbance is shown in the signal and the beam is in the middle of the screen but I can't move it up/down. This is under this time base not possible anymore!

I change all Electrolytic caps in the power supply but the problem is not gone away.
Where Is should search? I've download the service manual. Also the Battery is defect maybe this is a miss align problem. Did someone have the same problem? The failure is in all faster timings (time base 20us and faster) the same. If I turn the vertical position the signal is changing from down the line to upper the line but the line is not moving. What can that be?

Thank you and Best Regards
weakbit