Make sure you build the wear around the hole before you put a cliffy on, otherwise it will deform very quickly.  I use Selleys Knead-It - sets rock hard, and easy to shape before it goes off

Will do, thanks, hadn't thought of that.

Buying a pinball off eBay these days is like chook lotto.

As Rob said, build up the area around the hole before fitting a cliffy.

The monitor probably needs to be degaussed. These color distortions can be caused when moving the machine or when placing it next to items with a magnetic field. The motor in my Garage door does the same thing with arcade monitors. Could be a simple case of leaving it be as the chassis may degauss the tube over time anyway.

I think I'll eventually swap it for an LCD monitor anyway.