Cedric headlight problems

[77i9]

I have a JDM 96 Cedric Y33. It comes with dual headlights. The outer ones uses regular bulbs but are rigged to a dimmer. The inside ones are HIDs and they contain the highbeams. Well, the problem started when the left(passenger) side headlight quit working. It would sometimes light up for a couple of seconds and just die. So that kinda rules out the HID bulb right? Since it's HID I'm thinking it could be the ballast. Now comes problem No.2. Since one of the HID was not working, I decided to use the outer headlights. They worked fine for about a night and then all of a sudden no more lights. I have not checked the bulbs yet so I can't rule that out yet.
Any help or suggestions will be greatly appreciated! Thanks in advance!

[StealthSonic]

it maybe the ballast, bulb and ballast r not cheap. I would try the problem bulb on the working ballasts to narrow down the problems.

Outer bulb just have to physically check. If its ok it maybe fuse or bad ground.

Never touch the light bulb with bare hands. Clean it with alcohol if you have accidentally touch it to avoid grease on the bulb which would cause hot spot during the operation. Also if the bulb is not securely mounted to the housing, vibration could cause the fillament to break.