Hi.. let me see if I can help...
It sounds like the grid itself may have a blockage...
When the hot gas solenoid opens, it sends hot gas through the grid to melt the ice and harvest.
When the technic***** *****ged out the solenoid valve, did he change the whole valve or just the coil?
Did he place it under a vacuum? Did he purge the system?
His guages should have indicated that there was a blockage when harvest started because pressures would have increased from no gas flow...
It pretty obvious if you can see the ice sheet move up to a certain point.... but... let me be clear... if the blockage is there, you would see a freeze line on the grid. If hot gas wont flow neither should the cold, unless the blockage is partial and metering is occuring.
Unless you are a trained and licensed refrigeration tech, you should no attempt to repair the refrigeration portion of the machine.
Is the company you used an authorized agent of Scotsman? I know our techs are and Scotsman provides us training and technical support on their equipment.
The evaporators can be very expensive to change out and depending on the age of the ice machine, replacement may be the better option.
The ice thickness sensor would not effect only part of the grid.... the ice thickness sensor tells the machine to harvest at a set thickness.... the fact that the ice is not coming away from the grid evenly, indicates an issue in the grid...not the sensor.