What cleaner did you use in it?
I have a big StuellerSonic (2 gallon) machine that was refurbed. I use Mpro7 and L&R gun oil in it. I admit I don't use it that often but have never had a problem with it. It just takes a lot of time to set up and operate so I only do it occasionally when I really want to clean something.
My approach is fill the unit with Mpro7. Turn on the heater and dump the first gun in. I cycle usually 3 or 4 guns through it 15 minutes at a time and then change over to the L&R gun oil. While one of the guns is in the Mpro7, I hit it with a toothbrush, bore brush and the usual clean up. After the L&R gun oil (15 minutes, I drip dry the gun as it is quite hot. Oil, and put the grips back on. That is it.
I have run my painted guns through mine along with my Glock and a walther P22. I never had an issue.
I have heard that some cleaners are problems with aluminum and tritium vials for night sights but again, I have not experienced the issue. I think the issue is simple green but don't go to the bank on that.