Siter81,
I don’t want to disagree with Rocky, but if the drive was seized that would not explain the breaking cables as there would be no load on the cable inners. If the Speedo was seized or tight however, that may explain the breaking cable inners due to the front wheel drive forcing the issue against the tight Speedo. Oh, and if you use a drill to test it you can confirm that it’s working but the drill’s torque will hide any indication of stiffness in the Speedo’s mechanism, try inserting a cable end and spin it by hand.
Given that the cable break is only a couple of inches from the meter and if it’s at the same place, then I suspect the cause is likely to be a busted cable outer (flat spiral wound wires under the plastic insulating skin). If someone has exceeded the minimum bend radius for this cable during a hand fisted installation there’s likely to be an exposed broken outer wire rubbing and cutting it’s way through the inner cable as it spins. This would also explain the fluctuations caused by the friction and interference.
Any old how, I hope you find the cause and what the hey, give Rocky’s fix a go, these drives get neglected more so than chains and batteries, and it can’t hurt to give it some lovin’.
Rocket