Whilst the right hand indicator cancels the left never has in the whole time I've had it [6yrs or so),this morning it started cancelling, I couldn't quite get used to it so I was poised to turn it off but not needed on the outward journey. I told myself it was working only for it to stop again nearing home. I remember fiddling around with a soldering iron with some relays under the dash with mixed results on my 1st coop but never bothered with this one.
Typical Italian electrics!

It's more likely the nylon lugs are worn inside the unit. The central nylon ring self-centering catches them on self-centering, but it also has a certain amount of play.

If you remove the unit as per the how-to release the ring (held by four sprung legs) and pop an O-ring or two over it to take up the slack. It'll be trial and error to see what size - I ended up using two different gauges - it's been a long-lasting result for me as I didn't get on so well with building up the nylon lugs.

There are one or two other fine adjustments you could make at the spring end.