Using the set with the brightness turned up, and having no vertical
deflection can result in the line being burnt in to the screen. After
the
set is serviced, this is going to be permanent.

Thanks for the reply Jerry G. I also was curious to know what could
happen if it was used that way.

Considering the way you asked the question, my advice would be to get
the
set properly serviced by a service centre.

Yeah I guess I'll do that, I'm very new in the world of repairs but I
wanted to know what the trouble could be to know more about this
subject, and maybe soon I'll start to "fix" some things.
Thanks for your advice.
Greetings.