Dim keys on early MacBook Pro

Posting on behalf of a friend with an early MacBook Pro (I believe it's model A1226). Some of the keys have become very dim and he wants my help fixing it. He says the worst ones are 0, 9, L, semicolon, period and comma. I recall the keyboard on these models being a pain to replace but I haven't serviced the backlight. Does the keyboard need to be replaced to service the backlight or is there a better solution?