A Type Overdrive Problem

[nibby]

My A Type o/d works fine for the first hour,then it does what it likes. It cuts in and out of o/d on its own, then when I slow down for junctions,roundabouts etc the revs drop off then roar up to 4500 to 5000 rpm, like a clutch slip.
Am I losing pressure when the overdrive gets hot?
I changed the oil and cleaned the filter but rounded the bolt you access from inside the car under the rubber grommet near the gearstick(so have not cleaned operating valve)
Any help greatly appreciated.

[Richard B]

Try asking Overdrive Services in Sheffield.

[wakaday]

Check your wiring connections. The wires may have become brittle with age.