Long shot: Burroughs C3360 schematic?

[Josh Dersch]

Hey all -

Picked up a Burroughs C3360 calculator this week.  It's a programmable 
4-function+square root and 10-register memory with a nice 16-nixie 
display.  (See http://oldcalculatormuseum.com/bc3660.html)

I cleaned it out, and it's working fine in calculator mode, but in 
programming mode the program step counter is usually (but not always) 
stuck at zero.  Sometimes it increments properly for a few seconds after 
power-up.  Seems like a fairly simple fault to trace down, if I had any 
idea where to begin... anyone have a schematic for this thing (or the 
Sharp Compet 363P, which this machine is a rebranded version of)?  
Hopefully the fault isn't in one of the LSI chips in this thing, I'm 
guessing those are going to be hard to find.

Thanks as always,
Josh