I once had a similar problem on my old Sony Trinitron 15sf Monitor, it was 5 years old and i used to slap the monitor to make the tint go away it worked well

for a few days but then the tint started to change to green and later blue and again changed colors at regular intrevals... what dha hell!!....
... well my computer technician guy told me that it was my color IC chip or something thats got busted and he changed it and walla back to sweet normal mode infact better.....