Bloody hell, couldn't have made it up.. Thanks
There is a lot more to fixing the OSS that at first thoughts.
The main failure point is the nylon connector that connects the cable to the front truck, this in all honesty is simply a crap piece of design on the OSS
Audi (or more accurately the Co that Audi bought the OSS from) realised this design fault, but it was much too late as thousands of OSS had already been sold, the fix was a couple of metal plates that are screwed to the front truck and have teeth that grip the cable. These are still sold as 'OSS repair parts', but have a fundamental design flaw in that the OSS design transfers load from the cable to the truck via the cable pulling and pushing the nylon connector which as the other end of the connector attached to the rear foot of the front truck. So the load is push / pull from the cable.
When the nylon joiner breaks (which they all will due to the poor material selection) the Audi repair plates connect the cable to the truck in a totally different manor, the result is that the load on the cable is now a side load (as against the design intent of an end load)
Ultimately this will cause the cable to be pushed sideways against the aluminium rails (which it was never designed to tolerate) and as such once the hard anodising has been worn of the rails the friction will increase greatly adding much more load into the motor/cable interface which is already a weak point.
This is why my solution to the cable connector fault is to remake the cable ends in brass (instead of nylon), as such the loads are transferred as originally designed.
The other main failure point is the aluminium casting that the motor mounts too, this is made in two halves which are riveted together with pop rivets. For some reason the rivets are 3mm Dia but the holes are 3.4mm Dia, so this allows the two halves to move further apart resulting in the cables to motor mesh gap increasing. I remove the original rivets, increase the hole size to 4mm Dia and rivet with 4mm stainless steel rivets. This ensures that the play between the motor pinion and the cables is reduced to virtually zero, this as a dramatic affect on the 'drive' of the motor to the cables.
I am looking into the replacement of the aluminium castings with a CNC milled part which will eliminate this failure point totally.
As 'Audifan' as stated give the refurbishment of your own OSS some seriorce thought before you jump into it. I bought what I thought was a working OSS which I then found out was a broken sky, but this allowed me to refurbish the OSS in the garage and then fully test it before swapping it into my A2. To strip the OSS from the A2, do the refurb and then refit it all back into the A2 is not possible in a single day, so the A2 would have to be made water tight unless it can be garaged whilst the OSS is removed.
Pop around for a chat some time, there may be other A2 related issues that I can help you with, after all we are almost next door neighbours in the grand scheme of things
Cheers,
Paul