I used to have a R1800 and while printer technology has improved a bit it's capable of producing some great prints with pigment inks so I'd recommend sticking with it. I never had a cleaning issue like that but I did manage to resurrect a 4800 with a couple of tricks.
The first was soaking the head in windex. On the 4800 you can press a lever that releases the print head and allows you to move it across from the parked position into the printing area. I soaked some paper towel in Windex (the regular stuff that has ammonia in it) and folded it up and placed in in the printer then moved the head across so that it was sitting on top of the towel. I changed the towel out every day for 3 days - you will see ink on the paper to tell that it's working. I can't remember if you can move the head like this on the R1800 but I've heard that you can start an ink change cycle (so that the print head moves to the position where you can change the inks) then unplug the printer (don't turn it off first just pull the plug from the wall). After you have done that you can move the head.
The second method is purging prints. In between cleaning cycles run a purge print through the printer on plain paper. You can download them from here
http://www.inksupply.com/purging.cfm I always use a clean-purge-test process when getting rid of clogs on the 4800.
Last method is power cleaning. Not sure if the R1800 has this option but it's the last resort on the 4800 because it can use ~100ml ink!
Good luck, if you manage to fix it try to run a purge print through it every week and if you live in a dry climate placing a small cup of water inside the printer to give it a bit of humidity can help stop the heads from drying out (just remember to take it out before you turn the printer on!).
