OK - When I realised my watches had been removed (no explanation yet as to why) I went back in to the various forums I wanted to 'watch'. At each entry point, I clicked on the second tab (Content) and if you look at the right hand side of that resulting window, you will see a series of actions available. One is something like 'Receive emails .....'. If you are already set to watch this forum, it will say 'Stop receiving emails....' or something like that. Use this to check and if neccessary change the setting. You can do this at the top level of a forum (say for ALL CMDB related discussions) or down to a specific level you want to watch (say just Discovery). This has got me back onto the watches. And they have 'stuck' so far!