I've never had to do any work on a StyleWriter II other than unclog cartridges, so I haven't encountered your particular problem before. But there must be some sensors that detect the things it's complaining about. Disassemble the printer (I recall that it is very easy), and look for microswitches that would act as paper size/presence sensors. Do the usual tests (switch action, connector integrity, etc). If it's just a switch problem, you've lucked out. If it's a logic problem, then you're probably looking at a new printer.