Okay, so this is the third time I have had this problem in the past decade and I want to see whether I can fix it myself this time.

My cable has come loose again, so I have periods where I have no speedometer or odometer. Sometimes the speedo will come back on but the odo will not, or vice versa. Usually a stout hit of a pothole will cause this and another will fix it.

;^)

I had no speedo for three days and today I had to drive the brick for seven hours on the highway and the odo worked fine and the speedo worked most of the time, going out only for a few moments at a time about ten times total.

Last two times I was told that this was just something coming loose and not something that was broken. It was fixed very quickly and for little money.

But I now live an hour and a half from any Volvo indie shop and feel that this could very well fall under the "don't need no damned help" category.

First off, which wheel measured speed/distance? And how/where is it all hooked up? Is it an obvious problem or will I have to diagnose a bunch of stuff? Can I do this myself with "normal" tools or will some uber expensive, one-use-only special tool be needed? It seems to me that this ought to be a job for a small crescent wrench. But that is just my inexperience showing…

HELP!

(1990 740 base model, cam-driven distributor, if that matters)