I'm sorry to say, that I really don't know much about restoration of the speedo. I think the dry climate you might be living in is more rough to the speedo? To be honest, I haven't heard of any here in Denmark gone thru that much of attention to the speedo. Only the general problem with the paint for the front drying out and falling of..

As a matter of fact, I have had more than 40 120's thru my hands, none with a speedo broken...

Anyway, I would pay a visit to a local watch/clock-repair store and ask for hints for lubrication.. If you have a store like that ?

Air-brush lightly - shouldn't be anything else than dust in there. For electrical industry you can get a little spraybottle with a tiny brush mounted, for cleaning electrical switches and so - that would probably be a good method and cleaning-product.

Do it yourself! Thats a hole lot more good feeling afterwards! If anything really goes wrong I would ship you a complete nice used speedo for apr. the same amount.

/Soren