take the white and red spray caps, and after you have used one on the inverted can to clean it out at the end of the run, pull them off and leave them immersed in a small glass jar (capped with lid) filled with mineral spirits. The little bit of residual glue that seems to build up around the outside of the spray tip seem to flatten over the spray hole if left in-attended, and claring them out is not like picking a bit of paint out of the spray tip. Theu never spray properly again (experience speaking). Fish them out with needle nose pliers next time that you need them, give a quick squirt, and they are as good as if they have never been used before.
I use 77 to create all kinds of foam core studio props when clear tape isn't quite up to the task.