Speedo transducer problems?

[optimax sniffer]

When the cerb is hot, at low speeds the speedo stops working. As soon as I get above 20mph ish the speedo works again. I presume the txdcr is breaking down and is effected the heat and the moving airflow cools is enough to work again. Where is it positioned and is it easy to replace?

[Brummmie]

Its on the diff, you will see it on the toothed flange, drivers side.

[optimax sniffer]

Cheers

[jammy_basturd]

Noticed my speedo doesn't work below 20 leptons either, I half assumed this was how it was designed to work!