Don't ask why, if I tell you, I'd have to kill you
But with BMW/VW/Audi the VDO instrument clusters are essetialy the same. Rear plastic moulding containing the main circuit board (connectors directly mounted - so take care). Individual coils (and digital displays) pluged into circuit board through plastic moulding. Coils forward mounted onto clear prisms. Graphics glued to front of prisms. Nedles pushed onto coil spindles and hammered home with a single short knock. front binacle surrounds all and sits flush with graphics.
The needles can be a bugger to get off. The 'knock' is ment to be applied as with a torque rench but has the effect of very securely attatching it to the spindle.
If you get a ply tool, summit with 2 short prongs to sit either side of the spindle, base rest on the graphic (rem protection) and lever off the neddle, you could pull the spindle out the coil. Then your screwed, there a rela pane to get back in & calibrate correctly.
We used to apply a tool on the back of the prism, sitting around the spindle. The spindle should have a little brass/summit gromit type thing on it. If this is prevented from going any further forward when you try to ply off the needle, you should protect the coil. For this second tool, took a scalple blade, broke in two across the slot. Then wrap the blade end in tape. hold the tape end, and push the *now* open slot onto the spindle between the coil and the prism. It was just the correct size to stop the gromit/spindle bit from being pulled forward when you plyed off the needle.
We had about a 80% success rate. But this took alot of time, and we had limitless supply of replacement parts. All in all, I would recomend against it, unless you have a model makers hands and nerve and can afford to get the profesionals to sort it if it all goes wrong.
P.S. which gauges are hard and which are easy, depends on the gauge spindle width, the mchine tolerance knocking the needle on at the time, and any thread-lock type stuff that was in production at the time.