Hoshizaki Km-630MAB...not harvesting properly
So to begin, I am working on this unit that had first a burned out water pump so that got replaced and from there we found more problems with this unit. After running the first cycle, we noticed that not all of the ice dropped, in fact,maybe about 3/4 of the ice produced never made its way down. After talking to the owner, I was able to finally spill the truth and telling me that for 7 years he didn't do any cleaning on it and while checking the evaporator, we noticed build up. So it got cleaning 3 times in a row with brushes through the evaporator and the distribution tubes as well with the solution that Hoshizaki suggests. Once that got done, we ran the unit again and noticed that the ice harvest increased by maybe dropping more than half the load or so...but obviously not enough so after inspecting the evaporator for faults or damages and after also having cleaned the outdoor coil(That was done with the replacement of the pump, it was really dirty), it still did the same thing. I didn't want to put my gauges until i had reached a point where i couldn't see a problem and this was it. The few ice cubes that it dropped, the size was good and nice shaped cubes. I plugged in my gauges and could only see suction pressure. While we turn on, theres the water fill and then the harvest cycle turns on for about 3 minutes and the pressure read 40-45 psi on R-502. When i called the manufacturer it told me it should be reading 60-75psi and when it switched to freeze cycle after 3 minutes I let the machine run for some time. 10 minutes into freeze cycle i read the pressures and it started at 40psi and worked its way down to 21psi no lower than 20psi. Asking the manufacturer, they told me that this was right on. The time for freeze cycle is spot on between 30-35 minutes when it switches to harvest. But it is at harvest when it can't perform. I was suggested that it could be the txv and that i should replace it thinking that it may be letting refrigerant through and cooling off the defrost refrigerant (this was suggested by the Hoshizaki tech) I am just wondering to see if I can get any ideas on this unit because it's def. picking my brain. I just want re-assurance in the Hoshizaki people. Could I also be looking at the problem with the defrost valve?
Thanks for anyone's input.
If any more info needed i'll be happy to provide.