It has been a very long time since i have had an Ipotesi ign lock out. The memory is not so good these days i'm affraid!
I think that there is a little pin you have to push in to be able to lift the whole barrell out of the holder. I think you need the key in for this to work and iirc the pin is located at the base of the unit (best to do with dash removed). I will double check with someone who can remember better than i.
Re instrument rubbers. These are incredibly expensive and come from Ariete. The UK club was due to get some more in but i don't know if this has happened yet. If you can find an Ariete dealler in the USA they should be able to help, the part # is 02998 and they are the same for Speedo and Tacho. They are very slightly different to the originals but you wouldn't notice if i didn't point it out.
If you cant find any in the USA try Carrot Cycles in the UK as they are Ariete agents and very helpful www.carrotcycles.co.uk
Hope this helps.