Sounds like the pump is on it's way to pump heaven as you call it.
When a DDC pump start clicking, it's time for a new pump. Sure, in a mini-test loop the pump should run well. But, when under load and the loop temps are added, the click no-spin will happen again. The DDC-3 and DDC-3x pumps run around 100C+ under load. Now that's hot. A DDC-1T run about 57C under load and with a performance top about 4C more (61C).
A DDC blue impeller can fetch anywhere from $10 to $20 in the FS marketplace. Some people have ran the pump dry too long and burned out the impeller, seizing it up. Thus, a replacement impeller is needed.
With all of the DDC pump mods out there, nobody has ever made an improved replacement-drop-in impeller.
Anyways, A DDC-1T pump is cost effective in your case.