I have seen plenty of information and parts for later model 240, but mine is an 83 so I am posting here. Sorry if this has been asked/answered before...

The odometer in my 83 240 broke at 204016. I think it happened after pressing the trip reset button. Am almost 100% sure the car was not rolling at the time. I just left it that way for years and years since the speedo was fine.

Recently I mentioned this to buddy Larry at Rainbow Auto in Bellingham, WA and he just handed me a used instrument cluster and helped me install it. It had 202854 miles on it so pretty close. After install, I pushed the trip reset and it went to zero. Having read that it was a good idea, I pushed the button while moving slowly, not standing still. I then drove the car 119 miles with both odometer and trip meter working fine before I stopped to get gas. After fill up, I again pressed the trip meter while moving slowly and it again reset to zero as expected. However, I soon noticed that it too now refused to work. Just like my original.

So question #1, am I an idiot and doing something wrong? Or do I just have Murphy watching me too closely? Or do these all break regardless of mileage?

Question #2, it seems that instructions and parts are mostly out there for later vintage 240s and that my 83 is somehow different. I have only found parts on Dave Barton's page. And I am not 100% sure he has what I need since I have yet to open the speedo up in any way to fully diagnose the problem, count gear teeth, etc. In case Dave doesn't have what I need, can anyone suggest alternate sources for parts for the 83?

Question #3, I have some mechanical ability but no experience with speedo work. How likely is it that I can completely hose up the working speedo (with no odometer) that I have now? If there is a good possibility that I could ham-hand the thing, I could try to see if buddy Larry can find and ship me my original cluster so I could at least practice there.

Question #4, any other tips or things I should consider in doing this?

As always, thanks for your time and help.