I don't think you're going to find the speedo gear. I thought I remember reading in the last year or so that they are now made of unobtanium. After trying the usual suspects on this side of the pond (Dave Bean, r.d., JAE), You might try Alpine-America (
http://www.alpine-america.qc.ca/) as that is a Renault shop that caters to Europas. Failing that, you might try Richard at Banks (
http://www.banks-europa.co.uk/index.php). If you don't find it then, I think it's time for either a GPS or electronic speedo.
I'm assuming you're interested in keeping the general look of the Smiths gauges and in that case there are two options that I'm aware of, the SpeedHut GPS speedo and a Smiths electronic speedo. Here's a thread where this was discussed (
http://www.lotuseuropa.org/LotusForum/index.php?topic=1252.msg10930#msg10930). If you're not worried about keeping the general look of the Smiths gauges, they you can get any GPS or electronic speedo. Let me know if you have any questions.
Good luck!