The CM-SB, the HP-SB, and the HP-SBS all share a common side feed feature. While the side feed has many advantages over the top feed airbrushes, there is one vulnerability that many are not aware of.
This has to do with the small bend in the paint passage at the weld point of the side cup.
This is the point where the narrow paint passage takes a sharp turn
Should any foreign object pass through the paint passage there is a risk that it will become stuck.
Normally dried bits of water-based illustration paint that become stuck in this passage can be dissolved with ammonia. However, other materials can prove fatal to the cup.
One such material is cotton, which is found on a popular cleaning tool called a Q-tip, cotton swab, or ear bud.
If a tiny fragment of a strand of cotton breaks off and is allowed to enter the paint passage, the cup will be ruined and impossible to repair. I've seen this happen to dozens of cups over the past year, including a student's cup in my last workshop.
Never use cotton buds for cleaning your side cup. Instead use a twisted paper towel. The fibers in a paper towel are small enough to pass through the paint passage freely. Longer cotton fibers are not.
Good luck with your airbrushing!