After investigating my engine's OEM injectors further, I've decided that attempting to renew then by any cleaning and/or rebuilding process would be a waste of time and money. So I've decided to buy new ones; but they are not in my hands yet, so I'm not sure how this will work either. The OEM injector is no longer produced because of limited life expectancy and my failure experience is typical. My guess is that the manufacturer used units that would last about as long as the warranty period, and did so across a wide range of applications. Some examples of better units that both fit and meet the engine's needs are available and one of those is what I'll use. Building to meet the minimum requirements and standards is normally the case-- especially (but not limited to-- the RV industry), which is why I so far refuse to invest in a more expensive class A.
Thanks for your replies.