The pics should be self explanatory. What I think has happened is through either lack use of or just wear, the dials have seized. When I got it apart I put a drill on the drive and I could see it all spinning but just clicking where you can see the tip of the crewy. I poked a small screwdriver in-between each one and blasted away with wd40, lined them all back up and they seem to be turning easily now. Whether it's a permanent fix I don't know yet. I went steady with a fine dremmel wheel, cut gradually and you will get to see the white inner wall. Stop at that depth. Go all the way around, and prize away with a big screwy or a blunt chisel. I just eased the water proof shroud out of the reset wheel and once the screws are out of the back you can get your digits in.
This is the bugger
They do have a slot here but it does nowt. Someones had a go previously
Cut steadily all the way round
Prize this out, it's smegged in
Undo these
This is where it seems to be failing
I spun each dial as best I could with my finger then pushed a small screwy in-between them all and blasted with wd40. I set the trip to 0000 and put the miles back where they were. They are staying lined up and seem to be turning freely now, especially the trip which is all I'm bothered about really and would be happy if just that worked. The speedo works fine. I'm only going to duck tape the housing back together for now until I know it's sorted.
Excellent "how to" Steve! Let us know how it goes and, if all is well, how you decide to fit the top back on more permanently. I will then make this thread a "sticky"
Not without the chance of buggerring the whole thing up. The trip reset is held on by a circlip or similar and you need to get that off and withdraw it to get the lot out. Bit of a risk until until I get a replacement. All you can really do if spin the dials with fingers or bullnose pliers.