these 10 06 series Cdi's are probally hardest part on the mx to find, you will probally guess that as you see what else they fit.
IF you have a dead one , steve warne can still fix them but its about $200 or so. They only ever come up rarely and if they do on ebay they still get good money and with no sureity that a 35 yr old gel pack electronics will still be working right as they are usually of a breaker.
YOu can get aftermaket versions ( see lozza) but the debate is the ignition curves etc, at least you know with the originals they are right, although i have never seen these ign advance on a timing light so i dont think they do although the book says they do, so in theory a replacement should work fine, but hey who knows.
A whole PVL will set you back $4-600, inc stator, coil and black box, half the weight and 10 time more spark and spirit, might be a better option if you are keeping this bike.