Printed copies of drawing off centre.

I have been unable to get my LibreCad drawings to print on the centre of the page. More often, they are so far off that part of the drawing is missing.
What is the reason for this?

Also, the printed line thickness is so thin that it is almost invisible. The scale is also unstable and want to default back to a huge decimal point figure.

I must be doing something basically wrong. Can someone assist please?
This is what I am trying to print this morning:

hi Jim,

please try main menu File -> Print Preview

As described in http://forum.librecad.org/How-to-print-out-a-scaled-up-version-of-my-drawing-Solved-td5712558.html

you can use the button "center" or drag the Preview around by mouse

Yes, I did all that. Many times.

Are the lines really drawn with for instance 0.15mm, or maybe 0.00? Check with modify - properties.
In print preview mode the printing paper should be shown in white on your grey background. Where is it on your screenshot? Did the drawing look positioned right on the print preview? You can nail down the scale with the "fix" button. Is the paper size in current drawing preferences identical with the settings of your printer? Have you really printed on a physical printer or on a virtual (bitmap,pdf) printer (as I see "drilling guide 2.png" on the bottom of the screenshot) ?

just some thoughts