Wanted to update this thread with the resolution in case anyone else is having a similar issue. After trying two different sets of refillable cartridges and continuing to have problems with the cyan; I purchased a new set and the cyan is now back to normal. For some reason the PC cyan ink and the refill cartridges I bought from Amazon were not compatible (or my refill technique may be lacking). At some point I may try the Canon bottled ink to see if that works better with these carts, but for now I'm glad things are back to normal.