forcifer

well, 2 potential problems here: one, 1/4" tubing is tiny. i dont recomend it, but it is better then that. but for the real problem, you seem to have some algae. best way of cleaning it out is to take apart the block, rinse it with come clean water and, if you can get it, some kind of metal cleaner or mineral spirits. after cleaning it with whatever, it is very important to make sure it is 100% clean by re-rinsing it with some purified water to get out all residue.

just a warning, the block is going to be pretty gross to look at...