Well... here's how it goes.

Get your old indicator unit:

Now comes the difficult bit... I am using a spare set of indicators as the ones in my 2.1 were brand new a couple of years ago, and I don't want to ruin those... The mounting on these look reasonable, but they will need work, but I'm not bothered too much about having to make new fixings.

You need to fully remove the old lens. This is not easy as the original lenses are bonded in extremely well... the only option I found was to cut the lens round the outer edge with a Dremmel type tool, which left the edges attached to the unit. Once the front of the lense is out, the outer bits can then be removed with the same Dremmel type tool fitted with one of those metal wheels with teeth (like a rotary hacksaw blade).

Once what was left of the lens is removed you can tidy up what is left with the Dremmel type tool and one of those "sanding drums".

Here comes the next problem... the chrome plating on the back MUST be in good condition... unfortunately I could only find one unit that was good enough to use... For now, on the other spare units where the reflector is damaged, I am going to experiment with some chrome paint to see if this will form a suitable reflective surface.

Here's the new lenses:

And heres one trial fitted (with blutac):

Final fitment will require the lenses to be bonded in and be watertight, so I am going to try a silicone sealant similar to the stuff used on fish tanks.

Indicators finished and fitted to my 2.1.