Nanao ms29 blue screen

[@Alaska-]

A friend of mine got a nanao chassis ms29, which worked like a charm out of the box,

all of sudden after a power cycle, the image on the screen is completely blue with bluish hori lines

you can tell what game is running but the pic is very on the blue you can play at all

tweaking rgb pot doesn't help of course as i have a strong feeling this is a cap problem somewhere on the chassis or something blue line releated

any help would be very appreciated *___*U

[grantspain]

could be,
blue gain pot
blue drive transistor
blue gun in tube
colour decoder/amp ic