1969 Satellite/roadrunner style speedo problem

[uk-maxie]

Hi all,
A couple of years ago, while the car (69 Sport Satellite) was off the road having the engine replaced, the speedo needle somehow managed to move from being at rest at 0 mph to being at 25mph when stationary!
Consequently it's now indicating that we're doing approx 25mph more than actual speed.
We've tried lubricating up behind the speedo with no improvement.
Before we look at taking it all apart, has anyone else on here experienced anything like this?
My brother said he saw a couple of videos for cars for sale at Southern Motors and both had the needle stuck between 20-40mph when stationary and the seller said they 'sort themselves out' when the car gets going, but the videos didnt show whether they did or not.
Just wondering if it needs removing and a full investigation and rebuild or if there's likely to be an easy fix?
Any help gratefully received!

 

[uk-maxie]

Case in point...

"...that speedo will stick a little bit but it does work... the more you drive it, the better it'll get"!

Been using ours for a couple of years and it hasnt sorted itself out

https://www.southernmotors.com/Inventory/Details/5189#gallery-9

 

[69Bee]

The speedometer pointer shaft is supported between two points, and has a clockspring that will pull the pointer down to the peg. The cable drives a rotating magnet, and the magnetic coupling is what pulls the pointer higher. That being said, resetting the pointer shouldn't affect it, but I suppose if someone else took it off and got the spring tension off (or damaged the spring), it could do this. You could try to pull the pointer, rotate the shaft with the weight assy in the rear, and put the pointer back on so the spring pulls it back down to the peg. You might have to do it a few times because the correct pointer/spring position will put it at the correct spring resistance so that the rotating magnet has the correct pull to display the correct speed. Or, send the speedometer assy to a shop to repair and calibrate...