An old (ironic) joke in England states that you will stand around for an eternity waiting for a bus – only for three to come along at the same time! In the same way, dashboard faults sometimes do a similar thing. Recently I had three boards arrive; all had defective speedo/tacho motors. All six motors were physically broken and two electrically dead.
The motors mount to the circuit board by four soldered pins and two push-fit pegs. The arms on the motor case that grip the pegs break off and that leaves the motor pivoting 
on the four soldered pins. With time and vibration, the armature wires that are soldered to the pins flex and break – one dead motor.
Replacements are available from flea-bay for between £30 and £45 –not exactly a cheap part, especially when the old one may still be working fine. Now it seems a cheaper solution is available in the form of a replacement front cover (part with arms) for a fraction of the price of the full motor. On close inspection it doesn’t look like a 1-for-1 copy of the original (the arms are slightly different) but it’s well worth a punt at that price to see if it works.
So why are they failing? Well my guess is, it’s a combination of age, vibration and heat/cold cycling that causes the arms to fracture. Once that support has gone, the motor is left suspended on the four soldered arms – and they in turn are press-fitted into flimsy 
plastic spacers. The armature wire (very thin!) is soldered onto these pins, with very little slack ……. So any flex between motor and pins will inevitably stress the wires and cause them to break. They can be repaired of course, you just need good equipment, a magnifier and VERY steady hands!
Unfortunately, spotting a broken motor is difficult without striping the dashboard, but here’s a little something to look out for …… have a good close look at the needle, where it passes through the inlay. If the speedo needle looks like it’s drooping downwards or the tacho needle looks like it’s leaning to the left – suspect a broken motor. Remove the dashboard and give it a gentle shake – hear something rattling inside? That’ll be the broken arms floating around – tick-tock, tick-tock – it’s only a matter of time now before the armature wires give way!
