Hi there , welcome to Hexus.
Hard to say straight of , Hansol monitors were ok but time takes its toll on everything. Could but the tube or what they called the' EHT' or the monitor power unit that is causing your problem. . Can you not get a loan of a monitor to prove if it is definately the monitor that is at fault although I would suspect that it is. Try doing a 'google' on the monitor type and number , every monitor came with a user manual and that will tell you what the flashing power led means. If it does turn out to be the monitor it is not worth fixing as flat screen beasties are very cheap now. Try posting this problem in the 'help' section or hardware 'graphics section' as you may find someone that has had this type of monitor.