Is there any suction at all? If so, maybe get some really hot water and have it cycle that hot water through it to try and clean the insides. When I clean the water lines, I also run it for ~5 minutes in the kitchen sink with the lines into a bowl of really hot tap water.
The "Toms Aqua-Lifter" pump is a very common pump and should be able to be found at most LFS. For the time being, a single piece of airline on the top of the CPR placed below the waterline on the back should keep the syphion going once you get it started. Even if air gets into the line, it should just bubble out the back.