Hi Rolf,
thanks for the pic, seems like it's a Jones plug after all. It looks like they just drew a little square/rectangle to represent it on the schematic. Here's what I ended up drawing as I thought it was most likely a Jones plug, so I'll leave it at that.
How do I redraw it? lol, thanks for the kudos. Resample it to 600dpi in Photoshop for a start, then start drawing over the bluriness. I'm not sure why I'm doing this schematic, but somebody might find it useful one day. At least I learnt how to draw a sprocket properly in photoshop, and a hexagon. Both took a while to get the hang of but I've got it now.
You might have seen mrm_4's score card thread for his Rio machine. That pic was very blurry and a tough one to draw but we managed to get it done in the end, so your schematic doesn't look so bad, why do you find it unreadable? Send it over if you like and I'll see how bad it is. Doesn't look any worse than RecceDG's png file of his Solids n Stripes schematic. I might even redraw yours too if I get bored.
~ Mal ~
Jones Plug drawing.png