A belated update to this thread. This is a “for-the-record” post in case anyone is interested.
Short Version: I successfully replaced the capping station / pump unit, but serious problems that I was having wth the printer prior to the onset of the death rattle were not solved and the printer is now officially dead, for the second time. Replacing the capping station was not easy, but is possible if you follow the service manual and are slow and careful. There are a couple of stages when extreme care is needed (see below).
Long version: My R1900 had been a very reliable printer for eight years, but in its ninth year had become very cantankerous. The usual problems with desktop / small cartridge printers - large gaps in nozzle checks that come and go and move around, evidence of cross-channel bleeding in nozzle checks, ink drips on the page.
The IJM view on this forum has been to emphasise the importance of regular printer cleaning routines. My own experience made me suspicious of possible printer / refillable cartridge compatibility issues with small cartridge printers. Both views are probably right, the challenge being to know which problem you’re experiencing. When the capping station / pump unit (which the service manual oddly calls the ink supply unit) failed, I decided to test whether the problems had been a slowly dying capping station unit, or an intolerance to refillables brought on by old age. I was reluctant to discard a previously reliable printer without at least giving this a try.
Once the printer was back in operation with a new capping station unit and having had a clean under the head etc, I had a couple of good days with it, but then the problems described above reappeared and rapidly got worse. While some problems might be due to the printer needing a clean, as I suspected, if your printer doesn’t like refillables any more then you’re plain out of luck. As per my lessons post from some years ago. It’s possible that the new-style IJM carts might help, but these aren’t available for the R1900, and I decided not to try and swap chips on a spare set that I have here for another printer. I guess eight mostly good years is not bad.
On the issue of replacing the capping station & pump unit, it’s doable if you’re moderately handy and you follow the service manual slowly and carefully, but there are a couple of steps where extreme care is needed. The following references the R1900 - R2000 -R2880 service manual:
In the section 4.4.11 (p112) on removing the Paper EJ Frame Assembly, it’s a bit fiddly to get it out and even fiddlier to get back in. In particular you need to be vary careful of the two shafts either side of the EJ Frame and their connection to the L & R bushings of the CDR Release Lever Sub-assembly. The shafts click into the bushings, and I was clumsy and broke one of the bushings during reassembly. I was fortunate to have a long-dead R2400 that I used for prior practice and was able to cannibalise the broken part from. This reassembly step really has to be slow and careful.
The next step 4.4.12 CDR Release Lever Sub-assembly (p114) is also tricky. You have to partly dissasemble this sub-assembly in-situ in order to remove the screw holding it on, and then reassemble it before removing it, and somehow keep it together to prevent it coming completely apart. This is a real challenge, esp if you’re doing this for the first time. If you fail and it comes apart it’s not the end of the world. With a little ingenuity and plenty of time you can work it out, but it helps if you take a LOT of photos of the sub-assembly from various angles before this step to compliment the photos in the service manual. This is another step where reinserting the sub-assembly is even trickier and more fiddly than getting it out was, esp re-engaging it with the Paper EJ Transmission Lock Lever on the new capping station (Ink Supply) unit.
The Dissasembly Flow Chart (4.1.7 p75) suggests that you don’t need to do the Lower Housing / Printer Mechanism removal step 4.4.4 (p96). I think Harry Houdini would have trouble getting the ink supply unit out and a new one if you don’t. The R2400 manual recommends this step and it’s not that much more work to include it. The photos in the service manual imply that it’s been done, even if the text and flow chart omit it.