Lightroom :: ICC Printer Profile Stopped Working

Within Lightroom 5, I set up a print template for a new Canon ix6550 printer and used it for some months. I happily printed around 40 images.
 
I sold a few prints, and needed to print identical copies. Up until a few weeks ago, all worked fine.
 
Then, a few weeks ago, I tried to re-print 2 copies of a single image. The first copy printed OK (it looked like the original), I pressed the 'Print' button once more and the second print came out 'trashed' with extreme increases in saturation and contrast plus a decreased exposure.
 
I tried altering all sorts of things and printing test strips, but could not get a viable print.
 
I did not save any changes to the template or to the development settings of the images.
 
A few days later, I tried again. Without changing anything, the first test strip looked OK, so I went on to successfully print two A4 prints, then the third and all subsequent attempts to print resulted in trashed prints as described above.
 
Since then, I have determined that if I allow the printer to manage the colours, the test strips look fine. I don't know if I would see a difference on the full sized prints.
 
So I thought maybe the profile is corrupt? So I downloaded the drivers again from Canon and re-installed - no difference.(Although I do not know enough to locate and delete the originals first.)Should I let the printer manage colours? Will it matter?