I'm thinking about keeping the old refrigerator.
That would mean replacing the tubing from the
sink to the frig, which I not up for ... or plugging
the tubes and putting ice into the icemaker
manually ...

Is there a cutoff or a plug for the quarter inch
tubing? I think the tubing is stiff from age but it's
been there about 6 years, too soon for oxidation,
if that's what you call it?