Technical Twinair timing chain cover oil leak

[Liteboy]

We have a slight oil leak from the timing chain cover which I think is a common problem on the Twinair engine. My plan is to do it myself along with changing the water pump whilst I am in there. I have managed to get an Italian workshop manual in a pdf and have translated the sections I need to English so hopefully it will make sense.
Just wondered if anyone else had done this themselves and if there were any things to watch out for?