Moe, thanks for your reply and suggestion. As a result, I looked more closely into the front of the 1500 and discovered the means of opening it.
Unfortunately, it turned out that it was not a carriage stall situation; the situation is more fundamental and concerns some serious mischief with the circuit board components.
Perhaps I should have pointed out that this beast cost only $6.00 in a thrift store - perhaps they knew that the thing was a bummer useful only for some parts. I'll keep the corpse around for awhile; perhaps one with a busted case will show up.
I'd like to pose this question to all:
Would a Stylewriter 1200 print in color if I inserted the appropriate color cartridge and used Stylewriter 1500 drivers (which I am presently using successfully with the 1200)? Other than case outline, there appears to be no external differences in the mechanical layout of the two printers. Perhaps there is as far as the on-board chips are concerned.