faulty tilt mechanism?

One of the tilt mechanisms on my 2" wooden venetian blinds is failing.

As per the advice already on this website, I have removed the blind, and checked that the rod is firmly in place. I have also restrung the unit - all to no avail and so I have swapped a unit from a smaller blind which now nicely works the original blind.

My next step is to replace the faulty unit which is now in the small side blind. Unfortunately, the original supplier of the blinds has now completely vanished into thin air and so I am now not even able to invoke my rights under the guarantee that he gave me. Can anyone suggest where I might be able to source a replacement?

Many thanks

Where can I buy a new one? - it is a string pull system, and not wand operated.