If I don't install any external SIMMs, the page prints fine. However, if I
install any SIMM in any position, the printer will randomly crop off a

I have a 5MP. This model uses 72-pin SIMMs. It has three slots; two for
RAM, one for a proprietary combo RAM/ROM SIMM. I expanded my printer to
the full 19Mb of supported RAM by adding standard 60ns EDO DRAM 8Mb
SIMMs in the two RAM-only slots. I discovered from googling that there
are size-reporting jumpers on the SIMMs. (Some SIMMs don't implement
them at all; many just have blank pads and no jumpers installed, since
PCs don't require them).

I would guess that the printer is either misreading those size bits, or
your SIMMs have them set incorrectly.