Picture tube does not display full picture,Crackle from back

[Cruiseomatic]

I have a '53 Packard Bell 2723 that works well,But it does not show the complete picture. What I mean is, It cuts off corners and sides. I've tried adjusting everything I can see with no avail. What else can I do?
Also,I noticed a crackle from the HV cage and twice now its popped and the screen flickered and everything went back to normal. What could cause that also?
Thanks guys.