I have always heard part of the 'fun' of Amateur Radio, is self instruction. Since the MFJ-1786 Manual is readibly downloaded from several source; and the fact it goes into very detailed 'theory of operation', you probably don't really need a schematic drawing. Rather than a schematic, I'd suggest appealing to users, for someone to take good [and multiple] digital photos, then you can use them as a 'pictorial', and compare to your unit. Someone said 'a picture is worth a thousand words' ; and they can help, if you actually do a reverse engineering, and produce a schematic.