Temca Toilet repair procedure?

My Tecma toilet will not hold the level of water I want to set it at. Always drains to a low point. It seems to be widely known the cause of the issue is the discharge hose is pulled down to far.

What is the procedure to repair this? Obviously I need to raise the discharge hose but do I need to remove the toilet or what else should be done.

If anyone has actual experience with this please comment.
Thanks,