For the ringing on the left hand side take a look at RCA application note AN-151 which is available in the archives of the Electron One website. There's a wealth of historic information stored in those archives. Anyhow, AN-151 breaks down what can be the cause of that ripple and hopefully you can narrow it down to beam current modulation or modulation of the scanning current. Here's the link to the document.
http://www.one-electron.com/Archives...20Circuits.pdf