My 3800 (a good three years old) had its first major clog a couple of weeks ago. I was printing black-and-white prints using ABW, and they came out pale and with purple splotches (ugh!). Nozzle check showed that all inks were fine except black (PK at that point) which showed nothing at all. I did a couple of cleaning cycles and nozzle checks, no change. I removed, shook, and returned the PK cart. No change. I switched to MK and got the same result.
By this time I was panicking and expecting to have to buy a 3880, but I decided to try to RTFM first, instead. The manual suggested a "Power clean," which I have never done before. You can only do the power clean from the printer console, not from the utility software. So I tried a Power Clean and one more nozzle check:
Everything was now perfect!
So, before you buy a 3880, do try ONE Power Clean and a nozzle check, if you haven't already. It worked for me.