Info (and manual) about Schlumberger 5229 500MHz oscilloscope

[qzertywsx]

Good morning to all,
This is my first post in this forum, so excuse me for any errors and for my (very) bad english.
I have this oscilloscope, Schlumberger 5229, attached you can find a photo of it (Sorry for the bad quality).
I think that this oscilloscope have some problem with the trigger function, some time works and is perfect but some time didn't work at all and the waveform is not blocked on the screen , in the attached photo the waveform is perfect.
My question is:
Somebody have the manual and/or the circuit diagram? Or somebody know where I can find it?
This oscilloscope is a little bit different than the over I've used, so probably I'm using it incorrectly, the manual can help me to understand all the command.
Thanks in advance for any answer.