Looking for Silent 700 printhead

I have two Silent 700 terminals (model 745) that I bought quite a few years ago (nonworking). Couldn't find a schematic. Last week I just happened to search for one - and found a complete service manual with theory of operation and full schematics! So I got them on the workbench. The more worn one wouldn't print anything on the paper but was otherwise working. I found that the nylon printhead pressure adjustment wheel had split and fallen off the solenoid shaft into the case, along with the pressure spring. Then it would print, but I promptly discovered that the printhead has several "dots" missing in a pattern that could not be accounted for by the driver circuitry. I confirmed it by swapping the printhead from the other one, and now it prints perfectly. So at least I have one working now :) The second one in half-duplex mode will only beep (Ctrl-G), CR and LF in half-duplex mode, so I know the keyboard is alive and there is power. But it otherwise won't move the carriage forwards (including space), or print any characters at all. Before I go to the trouble of diagnosis and repair, does anyone have a good printhead, or know where I can find one? No point in fixing it if the characters won't be printing properly when I'm done... thanks Charles