Canon S500 problem with scaled prints

Archived from groups: comp.periphs.printers (More info?)

My S500 (up to now very reliable) has started giving problems if I try
to print a scaled down page. For example, if I print two A4 pages and
select two to a page, scaled to fit onto A4, landscape, the printout
is garbled, with bits of the text reprinted behind the real text. Any
printouts done normally, portrait or landscape, are fine.
The problem only seems to occur when the printout is scaled down to
fit more than one A4 page on a sheet and so printed in landscape.
I also use Fineprint to produce booklets; this uses the landscape
setting, with A4 pages reduced to A5 and printed two to a sheet; the
same problem occurs with this print setting. All was fine until I
replaced the empty black cartridge (which admittedly had sprung a leak
and lost a small amount of ink into the printer) and, from that moment
on, the problems described above began to affect the scaled down
printing.
I have cleaned the printhead and the internals of the printer.
Has anyone met this before and is there a reset code for this printer
( as with some Epsons) to return the printer to factory default
settings?