could be the tube is a little magnatized and needs degaussed too..
post a couple pics if you get time. Also make sure its wired correctly... ive seen colors look wrong like that(if its the whole screen) due to mis-wiring aka red is where blue should be and vise versa really messes everything up. Its worth your time to trace back all the way to the jamma harness connector, because its a red colored wire at the monitor pin does not mean it ends up at the correct spot on the edgs connector of the gameboard, who knows if that thins been hacked on etc...
heres how it should be pinned out at the monitor or at least the color inout wires should be this way..
(courtesy of modessitt)
Back to front: (in case you can't/won't check Ken's link)
10 - Negative Horizontal Sync
9 - Negative Vertical Sync
8 - Ground
7 - Key
6 - Positive Horizontal Sync
5 - Positive Vertical Sync
4 - Ground
3 - Blue
2 - Green
1 - Red
and here is a generic jamma pinout so you know what pin of the monitor wire should end up where..ignore the little box thats wired on this was made to show how to hookup a video conversion box
If you find your red and blue are switched, can be a simple of a fix as uplugging the 3 wire color connector, rotating it 180* and plugging it back in.