Ok, I got it figured out. I took the top piece off, the one that has the hose connections, thinking that was where the thermostat was. Wow, all kinds of junk in there blocking passage down and thru the thermostat. I took the thermostat out and flushed everything out good and put it back together. Will refill tomorrow after silicon dries.

As to the bubbling I was getting while blowing into the resivour tank, the air was escaping out of the small nipple at the top of the fill neck. I removed that hose and blocked it with my finger and no bubbling and system pressurized.

Thanks for helping me out with this.