Hi All,
I have a similar problem..
For the first few miles everything is fine,but the the OD off light starts flashing,and i lose my overdrive gear..also it seems to coincide that the 1st to 2nd gear change is eratic...sometimes at 2000rpm or 4000rpm...Took it to a garage and the tester diagnosed "internal gearbox fault"...really not convinved as it only started happening when i changed a headlamp bulb and touched the fuse box..its a lovely drive otherwise and would be a shame to scrap it???

Phil.