So far as I can tell, the PM15MD was a relatively inexpensive model in the AKG cartridge lineup, but I do seem to recall that AKG cartridges in general were said to have a propensity to lose output from one channel (see the long thread on MM cartridges started here by Raul). I don’t know why that was a common problem, but if it is due to an internal short circuit, perhaps one of the highly touted re-tippers mentioned here could fix it for you. On the other hand, unless you are in love with it, the repair cost is probably going to be more than the value of the cartridge. Meantime, there are many low cost cartridges, from Audio Technica and others, that are probably at least just as good. I suggest you consider a new replacement. I don't know why you say you cannot find a replacement, unless you mean to say you cannot find a working PM15D, another sign to look elsewhere and buy new.
