Thinkpad 390 backlight issues

[CKBourbon]

Hey all, I have a Thinkpad 390 with a backlight problem (Model 2626-70u, 14.1 " LCD). Sometimes it works, others it doesn't. It always lights on for maybe 1 second when I first boot the laptop, at the thinkpad splash screen, then goes out. When I attach an external monitor all is well, and if I cycle through the display outputs (LCD, CRT,BOTH) long enough, eventually the backlight will stay on, and after that it's on as long as the unit is....... Any ideas?