Source for schematics

Does anyone know of a good source for various car audio schematics? I'm looking for one specific schematic right now, but can't find any info on it. I've called the manufacturer and they no longer have any info on this series of products. For the record, this specific unit is a Sherwood XN-5000 active crossover that i'd like to modify to fit my specific needs, but i'd like to have the schematic before tearing into it. Any & all help appreciated. Sean

PS... I have "googled" using the make & model number. What i've come to find out is that Sherwood car audio was very big in Germany and a few other European countries.
Maybe here or here. It doesn't seem very likely, but one can only try. Cheers!
Thanks for the attempt Greg, i do appreciate it. I had tried one website already and was unfamiliar with the other. No luck at that one either. Sean