how dim? like you cant really read anything but can tell its still on? Is this an intermittent problem and now its serious? Provide more info if you want an accurate answer or one at all..... lol
Dim screen is normally the INVERTER needs replacing, but can also be the screen itself failing...
All the best Brett
Hopefully its the inverter because replacing the bulb isn't very fun at all! I just did one and I had de-solder a lead to take these little rubber bands off the other light and put them on the new one to keep the bulb from rattleing in the reflector. This flow chart helped out greatly....