Scotsman Ice Machine Revamp

I worked on a Scotsman ice maker over the weekend. I let it run 24 hours starting Thursday night. Friday morning nary an ice cube. This ice maker has an inverted mold. 2 spray nozzle continually supply water to the mold. When the cubes have formed the ice maker shuts down and flushes the res with water while flushing the mold with hot gas. The cubes fall out of the mold and into the bin. Every 20 minutes 6 new ice cubes are made. I had an idea this one was low of gas. Not very much heat coming from the condenser area and the water was cold but not freezing my fingertips. The machine runs on R134A gas. It only holds 5 ounces of freon. It already has some in it. If overcharged the line will be blocked and the compressor will bog down. So how much do you add? I attached a saddle valve and found the system was running in vacuum or in other words negative 10 PSI on the low side. I SLOWLY added a tiny amount of gas never letting the needle get above 10 PSI. When the pressure hung in there around 5 PSI without imediately going back into negative I quit adding and waited. It slowly dropped to 1PSI and stayyed there. In a minute or 2 it shut down and flushed the reservoir, shot hot gas into the mold and loosened up the ice. In the world of dead ice machines hearing the magic ka-thunk of an ice cube hitting an empty bin is a good thing!