I am not going to continue to respond to these messages (not that
anyone asked me to, mind you).
Much of Davy's conjecture as to what caused the failure of his
printers is indeed conjecture, and some is likely just not likely,
based upon my knowledge of the printers.
I have yet to see an Epson head damaged by air bubbles. An air lock
can cause the ink not to flow until it is corrected, however, although
rare since most of the time the purging process will remove the air
bubble.
Cleaning the heads more than 4 times in a row is likely quite
wasteful of ink, since after 4 times, the printer is likely not going
to unclog by those cleaning cycles alone, so it's a waste of ink,
which just helps to fill the waste ink pads, so why do it? I don't
think it is likely to damage the heads either. Epson does suggest
going through a cycle which does escalate the cleaning process, by
running a nozzle check between each cleaning cycle.