Well see there is already an issue, that bubble diffuser is crap, very poor design , no capacity AT ALL for the gunk really.
I am going to do that today infact, I will design something up.
maybe using 3/8-1/2" tubing instead of air-line, might help with the gunk
see check it out
Now I know it wont count bubbles since its designed to catch particles heavier then air and all, but you can add the syringe in line PAST the catch can, not only will it save your check valves it will also save the counter as well as alot of the line itself.
I know those take 3/8" line but they do make reduced fittings for smaller line such as vacuum line( air line).
Just an idea maybe there is something better then an water seperator for the air compressor to use but just wanted to throw that idea out there.