Hi Lee..If you do have to strip it approach the job with care The seal that is fitted to the case is retained by a combination of a light press fit and the body being 'staked' at two points..You have to be very careful not to terminaly damage the (unavailable) seal when prying it out. You can carefully remove some of the 'staking' with a dremel or die grinder. Once the seal is removed there are 4 very small BA screws that secure a thin steel retaining plate to the body. This plate holds the ring gear into the speedo body. Use a screw driver that is a good snug fit into the screw slots...Also the outer end of the screws tend to be burred over..I'm not sure if this was intentional at the assembly stage but it makes the screws tight to undo. Warm the speedo body in some boiling water before trying to undo the screws to reduce the chances of shearing the heads off.
Finally you have to remove the brass fitting that retains the worm gear shaft. A small C spanner or peg spanner would have been the correct tool to loosen this. You are unlikely to have anything that small and if you haven't got facilities to make one up you can grip the brass fitting in a vice using soft jaws and turn the body to undo the fitting. Again, warm the body before doing this...
After stripping, cleaning and replacing any worn parts (if you can find them) coat everything liberally with high temperature grease before reassembly...Ian
email (option): ian@wright52.plus.com