It's crazy to leave the flex cable until last - it's a known failure point (or should be by now, from customer and engineer feedback) and by far the cheapest and simplest fix, if it works. If it does prove to be that, you might try asking for compensation for the other 'unnecessary' replacements, though I don't know how far you're likely to get with that.
In my case the actual repairs were under a service contract but still cost me well in excess of £1000 for the new heads, new ink carts and maintenance tank that were needed. Adding insult to injury, the tech. tried three times to replace the right head with the old left head that I had just removed, having mistaken it for the new replacement and wasting yet more ink in the process, when in all probability neither head actually needed replacing at all. It does make you wonder how thoroughly some of these techs are actually trained. I did eventually manage to get some partial compensation from the service company towards the excess costs, but it was a tortuous and protracted struggle to get any sort of concession out of them and I was still substantially out of pocket at the end of it all.
These machines are incredible when they're working, but I do sometimes wonder whether they've now become just too complex for their own good, and/or if they are simply under-engineered and too fragile for that complexity, the propensity of Canons to blow major circuit boards as the result of a failed head if the 'replace printhead' warning is over-ridden being a prime example.
You're still way ahead of us in the UK, though; not only do your printers cost a lot less, but as far as I know, we don't have any sort of 'flat rate' repair option available. You either sign up in advance for a service contract at ca. £800 p.a. (+ VAT @ 20%), or you're on your own ...
I shall be very interested to see where this one ends up - hope you manage to resolve it without further major expenditure.
Malcolm
