Here is the parts breakdown
Replacement parts for INTERNATIONAL GT1727PACW | AppliancePartsPros.com

The frost at the back could indicate a defrost problem.
You have to remove the covers at the back of the freezer and check the evaporator coils. If heavily frosted/iced over you have a defrost problem.
Defrost problems show up first in the fresh food section and later in the freezer. Possible causes are defrost heater, thermostat or timer.

Also is the freezer fan running it is required, to push cold air down into the fresh food section.

The defrost timer is in the housing at the top of the fresh food section (Item 12 in the "Controls" section.
If you look up at it you should see a hole which allows you to turn the timer cam with a screw driver. It only turns one way.
Turn it till the freezer fan, compressor and it's fan shuts off
You are now in a defrost cycle
The defrost heater should come on.
One thing to note is that the defrost thermostat must be frozen as it opens and stops power to the heater just above freezing.
If the heater comes on then the heater and thermostat are OK and the timer needs replacing.
Be carefull that you do not burn your fingers.

If it does not come on then it could still be any one of the 3 components.
Disconnect the heater and measure it with a meter. Should be 30 ohms approximately.
If OK
Unplug and check the thermostat, should be approximately 0 ohms.
See page 2-16 in the following service manual. The defrost system is the same as yours though the manual is for different units.
http://www.servicematters.com/m...ibrary/docs/16010154.pdf
If OK
Then the defrost timer is shot re: it's contacts are not closing

If you do not own one I would suggest you purchase a meter. You can get a decent digital multimeter for under $20.00. You do not need fancy though it is nice if the leads are a couple feet long.
If it saves ordering one unnecessary part it has paid for itself and you end up owning a useful tool.
Most places will not let you return electrical parts so if you order it, you own it.
A couple things to watch when measuring ohms and continuity
1. Always remove power from the machine otherwise you could blow your meter.
2. Always disconnect at least one side of any device you are checking. This eliminates the possibility of measuring an alternate/parallel circuit path.
3. When checking for closed contacts and continuity use the lowest scale (Usually 200 ohms). Then try higher scales. This scale is 0 to 200 ohms so if the device you are measuring is 300 ohms this scale would show an open circuit which it is not, you are just measuring outside the scale's dynamic range.

There is a good STICKY at the start of this forum about it's use.