[ROVERNET - UK] P5 speedo function/repair questions

[Peter King]

Hi all.

My MKIII speedo stopped working recently. I suspected the cable, but 
replacing it did not solve the problem. I dismantled it this weekend 
and found that the plate attached to the indicator needle was making 
slight occasional contact with the lower element that is driven by the 
cable, causing it to jump wildly or stick in one position. When I 
loosened the four screws attaching the bottom to the top elements 
slightly, and shimmed the gap with a thin washer, the two elements 
stopped dragging on one another. I cleaned all surfaces and the bottom 
needle end of the indicator plate and reassembled with shims in place, 
and the speedo worked up to about 30 mph, then seems to be catching 
again, causing the needle to jump wildly.

Does anyone know if these units are serviceable, or if they simply need 
to be replaced once they go out of whack like this? The tolerance 
between the lower and upper plate is very tight, and I can only imagine 
that my tinkering with the distance between them would affect the 
accuracy of the unit.

I'm also curious to know whether the lower plate is magnetized, or does 
it influence the upper plate by creating vaccum? The upper plate 
appears to be made of aluminum. The lower plate has a magnetic charge, 
but I'm not sure if it's just static that is causing it??

Any thoughts on this are much appreciated.

Many thanks in advance,


Peter King

p.s. Anyone have a working replacement to sell?