[TR] TR6 J type OD hiccup

[Ian Viles]

The J Type overdrive on my TR6 developed 'hiccups' (repeated & intermittent 
momentary disengagement) in both 3rd and 4th gears towards the end of a 
recent 100 mile trip.  Today I took the car out for a drive with OD switch 
disconnected and wires connected together - OD still hiccuping - (more so 
when it had warmed up) - so its not the column switch at fault.
Where should I look next?
Thanks,
Ian Viles
1973 TR6 PI