According to :
I have an Amana side by side fridge - freezer unit. It is about 9
years
old.

The fridge door doesn't shut very well, and needs to be pushed shut to
get a
tight seal. (It used to self shut quite nicely.)

What (other than age) causes this and can it easily be remedied, or is
this
a sign that's it's time?

An appliance serviceman was interviewed on the radio some time
back, and said that by far the most common reason for this is
that the fridge case has twisted. Usually due to improper
levelling or the floor has sagged a bit. Cases on appliances
aren't very rigid, and can distort quite a bit.

Was visiting a friend last summer, and they were having the same
problem with a fridge after moving into their new home.

Remembering the radio program, I tried fiddling with the levelling
feet. A couple of minutes later, it was working perfectly.

The serviceman did say that sometimes the case will acquire a "set",
and you may have to overcompensate and wait a few days for it to
"unset".

You can try twisting it, but it's better to let it do it's own
thing once you've corrected the levelling problem.

Another possibility may be that the hinges have slipped (if there's
slack built into the hinges).
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.