For stubborn nozzle problem, one thing to watch carefully is whether anything you do changes the pattern. If despite all efforts the exact same nozzles are still missing, that’s a pretty good indication the internals of the head have gone bad or the head itself has been damaged in a head strike. If there is variation in the pattern of missing nozzles the problem most likely isn’t the head, and could be resolved with proper cleaning/moistening. If the missing nozzles are moving yet nothing seems to be able to get them all to clear, we have found a damper replacement often resolves the problem.
As far as the wiper, it can normally be kept cleaned and maintained quite easily, it really doesn’t need replaced unless it has been allowed to build up so much ink it won’t clean easily.
Additionally for any reading this thread, I can’t stress enough to not use Windex in the process of trying to clear a nozzle. Windex has evaporative agents and while they may temporarily dissolve hardened ink, it will re-harden quickly, and in such a way it may make the problem worse not better. There is also evidence windex can damage the internals of the newer heads used in the 78/9890 and 79/9900. Use only distilled water, or a solution such as that provided by AIS.
Last, for stubborn nozzles patience is required ... challenging sometimes because the job needs to get printed. But it may take saturating the capping station with AIS solution and letting the printer sit overnight.