I have an air cooled nde650(flakes) scottsman to play with. I have the service manual for the ice maker. By studying wiring schematics and parts diagram, I have gained some basic understandings how it works. I would like to study even more; anyone has the training manual for it? Is it OK to diable water level sensor and run it without running water to study it? If so, how do you disable it? I already tested it with water and worked fine. But, it is really inconvinant to hook up with water again. I also know that using a regular pressure gage is not good idea to check its pressure because that will drain some refrigerant each time you use the gage. Is there a good pressure gage that I can buy for that situation? thanks in advance.