I have a new Scotsman CU50GA that continually makes undersized ice cubes as a shell of an ice cube. I've tried all cube size settings (default, add: 1 min, 2 min, 3 min, 4 min).

cubes set too large
Adjusting the Ice Cube Size: 1. Press and hold the "Adjust" button for approximately 3 seconds until the Green Indicator starts blinking, release the button. The unit is now in Ice Adjustment mode. 2a. Press the "CLEAN" button to decrease ice cube size. The Red Indicator will flash as you lower in size and will blink when you have reached the smallest possible setting. 2b. Press the "MODE" button to increase ice cube size. The Yellow Indicator will flash as you increase the size and will blink when you reached the largest possible setting. After 10 seconds without any operation, the unit will return to the previous mode. NOTE: • During the ice adjustment mode, if the "ICE FULL", "ICE MAKING" and "ICE HARVEST" LED's all blink simultaneously, this means setting is at the regular (middle) size. • When the machine is in the cleaning stage or ice full stage, the ice size cannot be adjusted.

Open the door and remove the control cover, locate the cube size adjustment screw, to make fuller cubes turn the screw clockwise 1/4 turn this will make freezing cycle longer. only make adjustments in the first 10 min of the freeze cycle, this will bring the cubes to the correct shape. You can not make them any larger

There is usually a sensor that the cubes will touch after the cubes thickness builds to a certain point. This sensor should be adjustible.

Try cleaning the whole water system, then clean the condensor.

Check around the hot gas valve for leaks/oil.

Making good ice. Could be cube size control. Could be a weak compressor. Also these machines are household and meant to run in air conditioned space.

That has to be a faulty control wouldn't you think?
The cube size control should only be adjusted to
bring the cubes to the correct shape, the overall
size cannot be adjusted. Try to adjust the cube
size control when the ice machine is in the harvest
cycle, or in the first 10 minutes of the freeze cycle.
1. Open the door and remove the control box
cover.
2. Locate the cube size adjustment screw, and to
make fuller cubes, turn the screw clockwise about
1/4 turn. This will make the freezing cycle longer.
3. To shorten the freezing cycle and make cubes
that are not as full, turn the adjustment screw 1/4
turn counterclockwise.
4. After the next freezing cycle, the cubes should
have responded to the adjustment, if another
adjustment is required, do it early in the freeze
cycle.

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There is a cube size thermostat that energizes the timer. If it has been energizing early try a thicker setting on the cube size. If still gives problems ... your trouble was back in Feb I assume in cold weather.. If the machine is not in a room where the temp stays above 65'f this can also cause premature harvesting as you discribe also. Also if you are loosing water from the water curtian not sealing off it will cause the problem you discribe because the water is dripping off and out before it can freeze. Any futher questions please post. If this helps you understand your trouble please rate me as high as yuou can, thank you for using fixya

The older cubers were opperated by a cube size thermostat. when the temp reached the cube size tstat setting it would energize a harvest timer motor and this timer would continue running through a holding switch on the timer. when the cam comes around and the micro switch drops the water is introduced (it would be warm) and the hot gas from the refrigerant would be introduced to the evaporator causing the cubes to drop. at the end of the cycle the cam pushes op in the holding switch and finally open it and because the cube size tstat is now warm the timer motor stops.
The timer had a white plastic stem with a 1/4" D shaft. It would only turn clockwise. Try looking for this and advancing it to see if your sol valve will open or get voltage to the valve.

Check the bridge size adjustment at the top of the metal grid that the ice forms on. This determines the size of the cubes. Whenever you make a repair on the water system, especially on an older unit. make sure the unit is clean. A little bit of calcium deposits (or that other nasty looking stuff) getting into the passage ways will make it run erratically, and can drive you nuts.