Anything you add that can gunk up a leak can gunk up everything in the system – pumps, valves, exchangers.
Find where the leak is by using heat sensors and stethoscopes where the leak might be and isolate that tube by plugging it off the manifold.
The alternative is to rip up the section where the leak is and fix it.
http://www.heatpro.us energy businessmen’s knowledge
Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.