Mike, thanks for your help. I followed your guide and ending up adding about 3/4 of a cup of glycol/water mix to the loop to fill it. Clean cycle then ran with no issues after that! Thanks!!Somewhere back in this thread I posted a quick recipe you could use to check your system, however, its not necessary. I'd just go ahead and disassemble the unit and do a thorough clean and top off the glycol. It can't hurt and will let you inspect the lower end since this is a used machine.
The procedure I sent you is only for topping off the glycol, not for any mods. However, for a fill port, you would place a "T" connector between the HEX and the Glycol pump and run a length of tubing up the left side of the unit to a bulkhead fitting near the top. It acts as a small reservoir and allows filling without disassembly in the future. Look back in this thread a few pages and you can see/read about the basics.